User talk:Martin Hogbin

Edits to metre

Martin, I improved the wording of the spelling section and the opening paragraph to this article, it is annoying for someone to undo my useful work and cite some sort of consensus. I didn't remove any information and I made the article clearer, so I can't think of any consensus that would have been broken. Instead of hacking away at other people's contributions, it might be useful to make some improvements of your own to that poorly-written article. Owen214 (talk) 01:58, 7 April 2010 (UTC)

I have copied your comments to the metre talk page and I will respond there. Martin Hogbin (talk) 08:28, 7 April 2010 (UTC)

Edits to Talk:Speed of light

Hi, Sorry if I removed your comment, that wasn't my intent. Your edit to Talk:Speed of light made a double copy of every other section on that page, so I reverted it. (Look at the top lines of the page history, and you'll see that the page grew from 94 kbytes to 187 kbytes after you edited it.) I looked at your version to see if you had added an actual comment, but with such a long page I wasn't able to spot it, and in that situation the diffs from the previous version are no help. I just looked again and still wasn't able to see what you added. Sorry again. --Bob Mellish (talk) 18:55, 2 February 2008 (UTC)

Edits to Battle of Britain

Don't know if you meant to put it in, but you signed your name to the page. It's been removed. A bit more care, in future? TREKphiler 05:57, 10 July 2008 (UTC)

Sorry, it was a mistake, thanks for removing it.Martin Hogbin (talk) 08:11, 10 July 2008 (UTC)

Not a prob. Also, FYI, replies are usually to the poster's talk (except on article pages, where this form is usual), if you don't already know. TREKphiler ^{hit me ♠} 10:03, 11 July 2008 (UTC)

Editorial page

Re this comment: well said. TREKphiler ^{hit me ♠} 10:03, 11 July 2008 (UTC)

Re: Speed of light

Hi Martin. Alhazen carried out quite a lot of experiments with light to prove his intromission theory, so I think it would take up a lot of unnecessary space if we were to describe them in the speed of light article, but you can have a look at the Book of Optics article for descriptions of some of those experiments (I'm planning to add some more of his experiments to that article later on). Regards, Jagged 85 (talk) 13:53, 17 July 2008 (UTC)

A new approach

Dear Martin,

I read your comment on 'a new approach to lightspeed'. I do realise that problems arise from the use of another definition of velocity. The definition of the metre, being dependent on time (frequency, wavelength), has to be reconsidered. Or should our idea of time be revised? What is time? Does it exist, or is it being created continuously? Is time really to be considered the fourth (or zeroth) dimension? I don't know. I hope I'll live long enough to find out.

Kindly Regarding,

Jaap, Jay2U: Jay2U (talk) 08:40, 3 August 2008 (UTC)

Invention of radio

• See User talk:Anthony Appleyard#Invention of Radio. Anthony Appleyard (talk) 15:27, 3 August 2008 (UTC)

I notice that you have edited this article recently. I wonder if it article serves any real purpose in the light of the 'History of radio' article. I have started a discussion on the article talk page and your comments would be welcome. Martin Hogbin (talk) 23:36, 5 April 2010 (UTC)

My comments are in the history of that talk page. Since there's only one of me and an army of Teslaphiles with time on their hands, I'm not going to spend any more time on this. --Wtshymanski (talk) 13:07, 6 April 2010 (UTC)

Re: A new approach

Dear Martin,

The article about proper time has put many things into place.

Thanks, Jaap Jay2U (talk) 19:10, 4 August 2008 (UTC)

3RR

I think you need to step back and take a breather from Invention of Radio. Maybe shut down and walk away for a day ot two. Because you are close to breaking WP:3RR if you haven't already broken it.Swampfire (talk) 22:43, 4 August 2008 (UTC)

No, problem. I know what it is like to get wrapped up in a page and not pay attention to exactly what I am doing. Just bear in mind. To make sure it actually belongs, especially with the article being about a specific subject, and to always add from a NPOV, and make sure to include valid references.Swampfire (talk) 14:39, 5 August 2008 (UTC)

vos Savant's MH solution

Martin - vos Savant's case analysis solution is at http://www.marilynvossavant.com/articles/gameshow.html (which is in the external links section of the article). -- Rick Block (talk) 13:21, 29 October 2008 (UTC)

Talk: Gadsby (book)

Martin, would you mind re-formatting this edit? Replying in the middle of my comment messes up the numbering, and it's a little more difficult to follow the discussion when you are replying to unsigned parts of a comment. Thanks, and I hope we can remain civil in the discussion. -Phoenixrod (talk) 15:42, 3 November 2008 (UTC)

Existence of God (Tipler)

Please let me know your thoughts about the version of the article I have restored. Particularly whether there should be more content, or whether I should leave in the quote from Deutsch.--Jeffro77 (talk) 15:59, 6 December 2008 (UTC)

Mediation requested

A request for mediation has been filed with the Mediation Committee that lists you as a party. The Mediation Committee requires that all parties listed in a mediation must be notified of the mediation. Please review the request at Wikipedia:Requests for mediation/Speed of light, and indicate whether you agree or disagree to mediation. If you are unfamiliar with mediation on Wikipedia, please refer to Wikipedia:Mediation. Please note there is a seven-day time limit on all parties responding to the request with their agreement or disagreement to mediation. Thanks, Physchim62 (talk) 19:25, 12 December 2008 (UTC) Physchim62 (talk) 19:25, 12 December 2008 (UTC)

Request for mediation not accepted

A Request for Mediation to which you were are a party was not accepted and has been delisted. You can find more information on the case subpage, Wikipedia:Requests for mediation/Speed of light. For the Mediation Committee, WJBscribe (talk) 23:00, 12 December 2008 (UTC)

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Talk:Xiongnu

Thanks for responding to the RfC. My apologies, someone removed the diff I was wanting comments on: [1] Richard Keatinge (talk) 20:32, 16 December 2008 (UTC)

Speed of lightSandbox

Hi. I assumed your intention was to create this article in your userspace instead of mainspace, so I've moved it to User:Martin_Hogbin/Speed_of_light. I apologize for the inconvenience if this was incorrect. — Twinzor ^{Say hi!} 13:37, 27 December 2008 (UTC)

Twinzor, you were quite right, thank you for moving it. Martin Hogbin (talk) 17:54, 27 December 2008 (UTC)

Stuart Campbell

Just responded to a comment you made on the talk page. Thought I'd mention it in the event you'd forgotten. Seems like there's just the one editor with an axe to grind or a vanity article issue maybe. --88.108.243.214 (talk) 19:42, 29 December 2008 (UTC)

The worst problem, the unjustified linking of boycott with a share price fall, seems to have gone now. Martin Hogbin (talk) 10:50, 30 December 2008 (UTC)

Best wishes

Hi Martin, I don't see much of you on s.p.r. anymore. Apparently you more or less shifted to the Wiki. I wish you a happy, productive and healthy 2009! Cheers, DVdm (talk) 22:38, 1 January 2009 (UTC)

Re: "Is this a reliable source?"

Martin, I purchased this book at the University of Minnesota, in the physics aisle. But my regard for it as reliable has primarily to do with its contents. It is a quite simple diagramming of Einstein's treatment. I believe the website associated with it still has a lengthy pdf sampling of the book. - Ray

Rayclipper (talk) 00:42, 2 January 2009 (UTC)

Martin, see my user page. Thanks, Ray. Rayclipper (talk) 23:11, 2 January 2009 (UTC)

Monarchies in Europe

Hi, you made a comment on the Monarchies in Europe page. This article had many paragraphs of information on republicanism and these were reduced to one sentence in the interests of compromise. I hope you have a quick chance to review the reasons how the article evolved to this point over the past two months. Because of the way User:Cameron inserted the RfC tag, you may not have had the opportunity to see that the ongoing debate was actually in another discussion section. --Lawe (talk) 03:05, 13 January 2009 (UTC)

Poincaré

Hi, I restored the Poincaré-section in Einstein synchronisation. Why have you removed it? Poincarés contributions to this convention for clock synchronisation is well known (see the papers of Darrigol, Galison, etc).. --D.H (talk) 19:02, 5 February 2009 (UTC)

Maybe you are right. I put Poincaré into a "new" history section after Einstein, and changed the text a little bit. --D.H (talk) 22:27, 5 February 2009 (UTC)

Speed of light/Aether

Just a friendly note on Speed of light/Aether. This is in article space, and it's not an allowed use of subpages. (see Wikipedia:SUBPAGE#Disallowed_uses, #2). I've taken the liberty of moving it to User:Martin Hogbin/Speed of light/Aether. If you're working on this as part of a wikiproject, feel free to move it to a subpage of that project.--Fabrictramp | talk to me 20:42, 7 February 2009 (UTC)

Recent deletions on speed of light

You removed the paragraph below that was on speed of light claiming without any support that I have misread all the documentation. Here is the paragraph:

Outer space and ultra high vacuum approximate free space, but may have a non-trivial refractive index (that is, an index different from one). Ongoing experimental and theoretical work continues to explore the possibility of small departures of these mediums from free space, which could prove or disprove some theories of quantum gravity, or provide further corroboration of the predictions of quantum electrodynamics.

Personally I cannot see how any misreading has occurred. Here is a verbatim quote from Delphenich:

“Now, by the term "electromagnetic vacuum", what we really intend is not a region of space in there is no energy present, whether in the form of mass or photons, but a region of space in which only an electromagnetic field is present. Hence, there is some justification for treating the electromagnetic vacuum as a polarizable medium in the optical sense, which suggests that treating the electric permittivity and the magnetic permeability of the vacuum as simply constants, ε0 and μ0, is basically a pre-quantum approximation, as well as the constancy of the speed of propagation of electromagnetic waves, c0 = 1/√ε0μ0 , or, equivalently, the index of refraction of the vacuum. We shall regard these constants as asymptotic zero-field values of field dependent functions. The fact that c0 itself might vary with the strength of the field suggests that quantum electrodynamics might even have something deep and subtle to say about causality itself that goes beyond the familiar concepts of special relativity.”

Here's a quote from Moulin:

“This study is motivated by a desire to investigate the possibility of using recently developed powerful ultrashort (femtosecond) laser pulses to demonstrate the existence of nonlinear effects in vacuum, predicted by quantum electrodynamics (QED).”

Here's a quote from Marklund:

“The quantum vacuum constitutes a fascinating medium of study, in particular since near-future laser facilities will be able to probe the nonlinear nature of this vacuum. There has been a large number of proposed tests of the low-energy, high intensity regime of quantum electrodynamics (QED) where the nonlinear aspects of the electromagnetic vacuum comes into play…”

Here's a quote from Mourou et al,:

“The laser fields … will also enable one to access the nonlinear regime of quantum electrodynamics, where the effects of radiative damping are no longer negligible. Furthermore, when the fields are close to the Schwinger value, the vacuum can behave like a nonlinear medium in much the same way as ordinary dielectric matter…”

Here's a quote from Davis et al.:

“The most important magneto-optical interactions that can occur in material media are the Faraday effect, magnetic dichroism, and magnetic birefringence (the Cotton-Mouton effect). Quantum electrodynamics predicts that because of photon-photon interactions even the vacuum becomes birefringent in the presence of a strong magnetic field. …An improved experimental arrangement is needed to pursue vacuum magnetic birefringence and polarization rotation effects. With an improved system, detection of the QED- predicted magnetic birefringence should be possible …”

Where is the misinterpretation? What are you talking about? Maybe I should just do a series of verbatim quotes? Brews ohare (talk) 21:34, 12 February 2009 (UTC)

Martin, how about letting this small paragraph stand? It seems to be backed up by sources. Dicklyon (talk) 06:02, 13 February 2009 (UTC)

Martin, what are you up to?

Martin: You have not attempted to point out precisely what is objectionable in my paragraph above summarizing the above references. You simply ignore all appeals for specifics and continuously revert edits, be they posted by me or by others. I cannot understand your actions as intending to improve the article. They appear instead to be just acts of pique or of vested interest.

For example, here is the Delphenich verbatim quote with the changes made to introduce the term "classical free space" proposed by several editors:

“Now, by the term "electromagnetic vacuum", what we really intend is not a region of space in there is no energy present, whether in the form of mass or photons, but a region of space in which only an electromagnetic field is present. Hence, there is some justification for treating the electromagnetic vacuum as a polarizable medium in the optical sense, which suggests that treating the electric permittivity and the magnetic permeability of the vacuum as simply constants, ε0 and μ0, [(that is, as "classical free space")] is basically a pre-quantum approximation, as well as the constancy of the speed of propagation of electromagnetic waves, c0 = 1/√ε0μ0 , or, equivalently, the index of refraction of the vacuum. We shall regard these constants [pertaining to the medium of "classical free space"] as asymptotic zero-field values of field dependent functions. The fact that c0 itself might vary with the strength of the field suggests that quantum electrodynamics might even have something deep and subtle to say about causality itself that goes beyond the familiar concepts of special relativity.”

It is beyond my imagination how these insertion of the words "classical free space" detract from the meaning, and with this insertion the paragraph proposed says exactly what Delphenich is saying. Brews ohare (talk) 21:46, 13 February 2009 (UTC)

Speed of light: Are we there yet?

Hi Martin: A merged proposal is at Talk:Speed_of_light#Merged_proposal. Maybe you will like it?? Brews ohare (talk) 17:27, 14 February 2009 (UTC)

Helium

I came across this:

Helium, when it is breathed, increases the pitch of (parts of ) the human voice because it changes the resonant frequencies of the vocal cavities. It does this because the speed of sound is different in helium from that in air.

Martin Hogbin

I guess your intended explanation is right, but the formulation not. No pitch is increased, but the division of the energy over the present pitches shifts, whence the parts with the higher pitch become more audible. Nijdam (talk) 18:25, 16 February 2009 (UTC)

You guys both seem to be mixing pitch (psychophysics) with formant frequencies. Dicklyon (talk) 19:56, 16 February 2009 (UTC)

In what way does my answer suffer from that confusion? Martin Hogbin (talk) 20:28, 16 February 2009 (UTC)

Well, when you said "the pitch of (parts of ) the human voice", I suspect you meant "the frequencies of the formants of the human voice"; it may also affect the pitch, but not much. Dicklyon (talk) 02:34, 17 February 2009 (UTC)

Monty

As the "discussion" really gets chaotic, I address you here. I understand you are a strong advocate of the so-called unconditional solution. Of course, I hope, also to an unconditional problem. Let's first clarify that the formulation of the problem in which the numbers of the chosen door and the opened door are given, essentially form a conditional problem. I hope you agree on this. Please simply answer below with yes (or no), and I will continue from there. Nijdam (talk) 17:39, 16 February 2009 (UTC)

I am not sure that I can answer you question Nijdam, I have not thought much about door numbering. Martin Hogbin (talk) 20:29, 16 February 2009 (UTC)

Please try. You did a lot of thinking about this problem, so it cannot be to much trouble to clarify this point. Nijdam (talk) 22:54, 16 February 2009 (UTC)

I guess you would have to spell out exactly what the question is for me to answer. By the way I would rather have this discussion on one of the project talk pages. Martin Hogbin (talk) 23:18, 16 February 2009 (UTC)

Better not, because a thousand ignorants will fall over it and make a fruitfull discussion impossible. To spell out the problem exactly, means only writing down the formulation as given in the article:

Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat. He then says to you, "Do you want to pick door No. 2?" Is it to your advantage to switch your choice? (Whitaker 1990)

As you will well know, the numbers of the doors involved are explicitly mentioned. So to repeat my question; do you agree that this formulation, with the given numbers of the doors, essentially forms a conditional problem. Nijdam (talk) 00:18, 17 February 2009 (UTC)

I think may answer is no, on the basis that the host opening a door and revealing a goat does not change the initial probability that the player has chosen a car. Martin Hogbin (talk) 09:23, 17 February 2009 (UTC)

What conditional are you guys discussing? Condition of which door you chose first? If so, that's quite irrelevant as the that door can be relabeled numbered 1 without loss of generality. The important thing is whether the host's action in opening a door and offering a swap is unconditional or not, as it's left unspecified in the statement above; if he ALWAYS does, it's a very simple problem; if not, you need to know more about the conditional probability, or rules, of him choosing to do so or not. Dicklyon (talk) 02:37, 17 February 2009 (UTC)

Dick, have you read the discussion on the article talk page? If you want to continue this discussion, i suggest that we do it on the arguments page there. Martin Hogbin (talk) 09:25, 17 February 2009 (UTC)

@Martin: I hope you don't mind, I indented your reply to keep it apart from others. Now about your answer. As you say no, I think we need to specify the probability space. Will you do this or do you accept I write it down? Nijdam (talk) 09:59, 17 February 2009 (UTC)

After you. Martin Hogbin (talk) 17:35, 17 February 2009 (UTC)

The sample space consist of 18 outcomes, represented by the columns of this scheme:

chosen  K:   1  1  1  1  2  2  2  2  3  3  3  3
car     A:   1  1  2  3  1  2  2  3  1  2  3  3
opened  O:   2  3  3  2  3  1  3  1  2  1  1  2
---------------------------------------------------
probability  1  1  2  2  2  1  1  2  2  2  1  1 /18

The last row gives the probability function, each entry to be divided by 18. For simplicity we may write [132] to indicate the 4th column, with the meaning: chosen Door 1, car behind Door 3, opened Door 2. The stochastic variables K, A and O speak for themselves and may eventually be used for ease of notation. Agree? Nijdam (talk) 23:05, 17 February 2009 (UTC)

OK Martin Hogbin (talk) 23:12, 17 February 2009 (UTC)

I didn't deliberately made a mistake in the probabilities, but I have corrected them. I will refer to this probability function as $p_{0}$. I.e the prob. the car is behind door 1 is:

$P_{0}(A=1)=p_{0}([112])+p_{0}([113])+p_{0}([213])+p_{0}([312])={\tfrac {6}{18}}={\tfrac {1}{3}}$.

And the prob. the car is behind a door that is chosen is:

$P_{0}(A=K)=p_{0}([112])+p_{0}([113])+p_{0}([221])+p_{0}([223])+p_{0}([331])+p_{0}([332])={\tfrac {6}{18}}={\tfrac {1}{3}}$.

Hence the prob. the car is behind one of the two not chosen doors is:

$P_{0}(A\neq K)=1-P_{0}(A=K)={\tfrac {2}{3}}$.

Right? Nijdam (talk) 11:22, 18 February 2009 (UTC)

As you didn't answer till now, I guess you agree on this. Now there is an aspect of the problem, we didn't notice till now: is it necessary the choices of the doors occur random. i.e. with equal probabilities? I would say: unimportant. agree? Nijdam (talk) 10:39, 19 February 2009 (UTC)

You'd be better off keeping this on the article talk page as Martin had suggested. As to whether the initial prob distribution is important, yes, very; if you know the probability is heavy on doors 1 and 2, for example, then always starting with door 3 would be a great strategy. If you mean does the initial distribution affect whether always switching is a winning strategy, probably not, but you'd probably need to do some work to prove that. Dicklyon (talk) 16:10, 19 February 2009 (UTC)

Well, my guess is, it's better off here, otherwise it would drown in all the comments of others. I see, I didn't make myself clear: I meant only the distribution of the door picking (choice) by the player. I would say that it is irrelevant. Nijdam (talk) 17:19, 19 February 2009 (UTC)

Sorry Nijdam but I really do not think I can be of much use to you here. I am not expert in the theory of probability and I am not terribly knowledgeable of its notation and mathematics. I think the real problems come from the way the way the question is formulated. Although I originally accepted your sample space, I now feel that I should ask why it does not include other possibilities, like the words used by Monty. As you know, these are being discussed elsewhere. Martin Hogbin (talk) 23:34, 19 February 2009 (UTC)

Please Martin, have a look at Talk:Monty Hall problem/Arguments‎ where I gave an example of a simplified problem. And as for your question of including other possibillities: I might have, allthough they are not part of the problem, but they are irrelevant to the problem and do not change the conclusions. Nijdam (talk) 11:47, 20 February 2009 (UTC)

Again, Martin, please read the section Talk:Monty Hall problem/Arguments‎#Simple play.Nijdam (talk) 18:40, 20 February 2009 (UTC)

MontyGill

Hello Martin (and Nijdam). Thanks for the message on my talk page. As a "professional" I have had a professional interest in the Monty Hall problem for quite some time. The first time I heard it, I gave the wrong answer. It's a beautiful paradox. However it was only recently that I became aware (through wikipedia) that there was this big issue about a conditional versus an unconditional formulation of the problem.

My current standpoint is the following. I assume till further notice that the player chooses his door uniformly at random, and that the quizmaster (who knows the location of the car) always opens one of the other two doors displaying a goat. With these assumptions, the probability that the car is behind the other door is 2/3. My informal argument for this is that when the game is repeated many times under these conditions, in 1/3 of the times the player is standing at the door with the car, 2/3 of the time standing at a door with a goat. On the first 1/3 occasions the car is never behind the other closed door; on the other 2/3 occasions the car is always behind the other closed door. This verbal argument which I think everyone understands can be converted into a mathematical proof, if you feel the need, by simply writing it out in formulas.

Prob(other closed door hides car) = Prob(other closed door hides car | first choice was correct) x Prob( first choice was correct) + Prob(other closed door hides car | first choice was wrong) x Prob(first choice was wrong) = 0 x 1/3 + 1 x 2/3

On the other hand, under the same conditions, the probability that the other door hides the car given that you have chosen door 1 and the quizmaster has opened door 2 depends on the quiz-team's strategy for hiding the car and the quiz-master's strategy of which door to open. The quiz-team's strategy consists of the three probabilities adding to 1, for putting the car behind doors 1, 2 or 3. The quiz-master's strategy consists of probabilities (adding to 1) for opening door 2 or 3 when the player has chosen 1 and the car is behind 1, probabilities for opening door 1 or 3 (adding to 1) when player has chosen 2 and the car is behind 2, and probabilities for opening door 1 or 2 (adding to 1) when the player has chosen 3 and the car is behind 3.

In particular, Prob(car is behind 3 | player chose 1 and QM opened 2) = Prob(car = 3 & player = 1 and QM = 2) / Prob(player = 1 and QM = 2) = Prob(car = 3) x 1/3 x 1 / ( Prob(car=3) x 1/3 x 1 + Prob(car = 1) x 1/3 x Prob( QM = 2 | car =1 = player )).

Let me make the assumption that the quiz-team puts the car behind each of the three doors with equal probability 1/3. I suppose the player chooses his door independently of the location of the car; it now doesn't matter what probabilities he uses, as we'll see! Then we get

Prob(car behind 3 | player chose 1 and QM opened 2) = Prob(car = 3 | player = 1 & QM = 2) = Prob(car = 3 & player = 1 & QM = 2)/Prob(player = 1 & QM = 2) = Prob(car=3 & player =1 & QM = 2)/(Prob(car=3 & player =1 & QM = 2) + Prob(car=1 & player =1 & QM=2)) = Prob(QM = 2 | car=3 & player =1) / ( Prob(QM = 2 | car=3 & player =1) + Prob(QM = 2 | car=1 & player =1) ) because Prob( car=3 & player =1) = Prob(car=1 & player =1) . Thus the required conditional probability equals 1 / ( 1 + Prob(QM = 2 | car=1 & player =1) )

This can be as small as 1/2 and as large as 1, as we vary Prob(QM = 2 | car =1 = player ) from 1 down to 0. So the conditional probability is not fixed without specifiying the quiz-master's strategy, but it is always at least 1/2. Therefore, conditionally on the player's information, it is never to the player's disadvantage not to switch doors (sorry for triple negative). And to reach this conclusion, all we had to assume was that the initial location of the car was uniform at random.

Gill110951 (talk) 23:32, 27 March 2009 (UTC)

Ok, R., nothing new to me. Rick Block and me have given this analysis in different forms over and over. The point of discussion stays. The so called unconditional "solution" doesn't solve the posed MHP. Look at it from this side: you're standing next to the player. She chooses one of the doors and the quizmasters opens one. From that moment on they are not just any doors, but specific known doors. And the player has to decide in the situation she's in, i.e. given the specific chosen and opened doors. That's why in the formulation of the problem it reads: say No. 1 and say No. 3.Nijdam (talk) 09:43, 28 March 2009 (UTC)

If I may interject here -- that's true, but the problem as stated is strongly suggestive of the possibility that we are in a situation with a certain symmetry, in which the specific door chosen by the contestant and the specific door opened by the host are not expected to changed the probability of the outcome. With this traditional interpretation, the unconditional solution does solve the problem correctly; all we want is to present the simple traditional solution first; after that, you can comlicate the problem and provide the correct solution for the problem lacking such symmetry. Dicklyon (talk) 14:46, 28 March 2009 (UTC)

It's strange that you don't understand the difference. When you say: it solves the problem correctly, you seem to suggest it produces the right answer. And that is true. but it doesn't do this in a proper way. So it does not explain the answer. I than say: it does not solve the problem. Nijdam (talk) 20:09, 28 March 2009 (UTC)

There seems to be some disagreement over whether the Morgan paper refers only to the specific case where the player picks door 1 and the host opens door 3. It seems that Dicklyon and Nijdam agree with me that the Morgan paper refers only to this specific case but Rick Block believes that the Morgan paper somehow applies to the case where the host has opened either door 2 or door 3. Martin Hogbin (talk) 15:42, 28 March 2009 (UTC)

I do not claim any originality. I have not read the sources. I have not studied the wikipedia discussions. I am not well motivated to study poor solutions (even if published in peer reviewed journals) to badly posed problems.I have simply used my brains and my professional knowledge and written out what I believe can be said. If all we are willing to assume is that the player picks the good door with probability 1/3, then all we can conclude is that (unconditionally) the probability the car is behind the other door is 2/3. If all we are willing to assume is that the car is hidden with equal probability behind each door, then we can affirm that conditional on the player's and the QM's choices, it is never to the player's disadvantage to switch doors, and it might be greatly to his advantage. Conversely, if you want unequivocal unconditional and conditional answers respectively, then there are different minimal sets of assumptions which have to be made. Now it is not clear that in a short verbal description of the problem "..., e.g. door 1 and door 2, ..." implies that we are actually being asked to solve the problem conditional on these choices. Did the person who asked the question understand the question and understand the answers? A mathematician's job is to figure out which questions make sense. It is much more interesting to find the right questions than to find the right answers. But anyway, we know that if you want certain questions to have an unequivoval answer, then you are going to have to make some assumptions, beyond what is strictly implied by the wording of the informal question. I do think that what I have figured out about the game-theoretic approach is new and interesting, though of course it is very elementary, and I plan to turn my draft (pdf on my website) into a serious paper. Gill110951 (talk) 17:14, 28 March 2009 (UTC)

Sorry R. Use your professional knowledge! If the car is put randomly, the probability it is behind door 1 is the same as for door 2 and door 3. All 1/3. So for any other door the (unconditional) probability the car is behind it is 1/3. The problem you are faced with is of course having written this paper. But at least admit that a right question may be: if door 1 is chosen and door 3 opened showing a goat, what to do? This is the situation a player might find herself in. Or any other combination. It is also the charm of the problem. If the host uses the random strategy, the player has to use extra symmetry arguments to reach the conclusion that for any situation she may find herself in, she wins the car with conditional prob. 2/3 when she switches. But notice: she considers every situation she will meet. Which means that her conclusion is that in all situations the conditional probability is the same and hence numerically equal to the unconditional. But it is the conditional probability she bases her decision on. Choosing and opening means conditioning. State any other problem and solve it, but in the MHP the player is on stage, points at a door and another door is opened and shows a goat, and in this situation she has to decide. Nijdam (talk) 20:09, 28 March 2009 (UTC)

@Nijdam: I agree that a question a player can be faced with is that, having chosen door 1 and door 3 opened showing a goat, she has to decide what to do. Indeed she is now interested in the conditional probability of the car being behind door 1 or 2. In order to compute conditional probabilities we need some probabilities to start with. I think of the game as proceeding in three stages, each of which can be random: stage (1) location of the car by the quiz-team, stage (2) choice of the door by the player, stage (3) choice of door to open by quizmaster. I suppose that stage (2) is statistically independent of stage (1). Stage (3) can involve any conditional probabilty distribution whatever. It is now a fact that if (1) is done uniformly at random, then (2) doesn't matter, and whatever (3), it is not to the player's disadvantage to switch, since the conditional probability you and I are interested in is greater than or equal to 1/2. If on the other hand (1) is not the uniform distribution, then there is not so much one can say. But one can say that if the player chooses her door at random, her unconditional chance of winning is 2/3. And I think it is interesting that the uniform strategy of the quizteam and the uniform strategy of the player are minimax ... But you are welcome not to find this interesting.

My paper is not a paper, it is a draft, and I benefit from discussions like this, so the next version will be even better. Thanks!

Finally, as to what is "the" MHP problem, that is a debate which I'm not qualified to participate in, since I did not read the original references. Even if I did, I might well want to criticize what those original authors have written. In particular I get the impression that I would not much like the Morgan paper. Gill110951 (talk) 01:11, 30 March 2009 (UTC)

Ok, R. Switching is under the conditions you mention always advantageous. But how does the player know this? Because she calculated the conditional probabilities. That's where she bases her decision on. Not on the unconditional 2/3 when switching. If she argues using the unconditional probability, she needs at least some extra arguments, involving the conditional probabilities, perhaps without actual calculating them. But the conditional probabilities are the ones used for her decision. With the player, I mean of course the player on stage who made her choice and whom the quizzmaster has opened another door. I do not mean a player in general. The average player will win the car in 2/3 of the cases when switching, but an "individual" player might have different chances, depending on the quizzmaster's strategy. For the average player the unconditional pobability is sufficient, but the individual one needs the condition. Agree? Nijdam (talk) 08:56, 31 March 2009 (UTC)

Please R., before this turns out to be a problem of wording, formulate the problem and solution in this terminology: number the doors 1, 2 and 3; let C=door with car, X=door chosen initially, A=door opened by host. Assume: P(C=c)=1/3 and P(X=x)=1/3 (although unimportant), C and X independent. Then what?Nijdam (talk) 20:47, 28 March 2009 (UTC)

@NIjdam: I don't wish to assume what you have assumed, and on the other hand, I think it is important that C and X are independent. We are interested in the situation where the quizmaster and the player are not in collusion and are not able to read one another's mind. Gill110951 (talk) 01:11, 30 March 2009 (UTC)

Thank you Martin, for your words in Talk:Monty_Hall_problem/Arguments. You are right: I found your "critique of Morgan et al." and I appreciate it as an important aspect for the MHP article. Regads, -- Gerhardvalentin (talk) 00:42, 5 March 2010 (UTC)

Italics in Speed of Light

I reverted your undo as you provided no reference for your argument and started a discussion on the SoL talk page here. If you would like to discuss it, please do so there.OlYeller^Talktome 16:54, 26 February 2009 (UTC)

Noah's Ark FAR

I have nominated Noah's Ark for a featured article review here. Please join the discussion on whether this article meets featured article criteria. Articles are typically reviewed for two weeks. If substantial concerns are not addressed during the review period, the article will be moved to the Featured Article Removal Candidates list for a further period, where editors may declare "Keep" or "Remove" the article's featured status. The instructions for the review process are here. --Vassyana (talk) 15:35, 20 March 2009 (UTC)

File copyright problem with File:Monty-MiddlePickCar.png

File Copyright problem

Thank you for uploading File:Monty-MiddlePickCar.png. However, it currently is missing information on its copyright status. Wikipedia takes copyright very seriously. It may be deleted soon, unless we can determine the license and the source of the file. If you know this information, then you can add a copyright tag to the image description page.

If you have uploaded other files, consider checking that you have specified their license and tagged them, too. You can find a list of files you have uploaded by following this link.

If you have any questions, please feel free to ask them at the media copyright questions page. Thanks again for your cooperation. Radiant chains (talk) 12:11, 30 April 2009 (UTC)

Separate page for discussion of Twin scenario itself

Please reply to my comment, if you don't I will delete the section and the page it links to. Paradoctor (talk) 12:02, 1 May 2009 (UTC)

Häggström-creep

If Haggstrom or his supporters are going round adding images to articles that will not benefit from them then I agree that this should be stopped, however, if the consensus of editors on any particular article is that a human image would be helpful then I see no problem with using his. Martin Hogbin (talk) 09:07, 21 June 2009 (UTC)

I agree that the image in the copper article is somewhat superfluous and I have deleted it. Let us see what the reaction of other editors is. I think that oxygen plays such a vital role in human life that a diagram is justified here. I can see this image getting out of hand and we should all try to stop that but I have no objection to the concept. Martin Hogbin (talk) 09:16, 21 June 2009 (UTC)

For this purpose a diagram in which a human silouette figures, might be helpful, but why a recognizable person, and why somebody recognizable as Häggström?? This stuff is growing like Kudzu. You want another? I see he now has his face stuck in the Wiki on gold, even though gold toxicity does nothing to the face. So now you have yet another article to look at. SBHarris 21:50, 19 July 2009 (UTC)

contact?

while looking into the 'fundamental importance', i stumbled onto this post & as can be expected, figured i should talk to you. have anything to share? hoping to get into media & make something abit more legendary. bandaidsrcool@yahoo.com —Preceding unsigned comment added by 68.62.46.149 (talk) 10:19, 26 July 2009 (UTC)

The Speed of Light

Martin, I left a note on Brews's talk page which equally applies to yourself. You may as well read it rather than me writing it out again. If you could both openly declare what is driving you in this argument, I might be able to suggest a way forward. David Tombe (talk) 11:57, 1 August 2009 (UTC)

August 2009

You currently appear to be engaged in an edit war according to the reverts you have made on Speed of light. Note that the three-revert rule prohibits making more than three reversions on a single page within a 24 hour period. Additionally, users who perform a large number of reversions in content disputes may be blocked for edit warring, even if they do not technically violate the three-revert rule. If you continue, you may be blocked from editing. Please do not repeatedly revert edits, but use the talk page to work towards wording and content that gains a consensus among editors. If necessary, pursue dispute resolution. tedder (talk) 22:54, 14 August 2009 (UTC)

Tedder, before you get too heavy handed with me you might like to take a look at the history of the 'Speed of light' to see what I am trying to do. The page was once an FA and I am trying to get that status back by steady, cooperative editing. Unfortunately, there are a couple of editors who are using the page as a soapbox for their own extremely unconventional views on the subject. I can see no way round this attempt to subvert but to revert edits that are essentially crackpot science. Martin Hogbin (talk) 08:03, 15 August 2009 (UTC)

Naming conflicts proposed changes RfC

Those wishing to radically change the WP:Naming conflicts guidance have set up a position statement/poll at Wikipedia_talk:Naming_conflict#Positions as a prelude to RfC. Since you have expressed a view on this guideline and have not so far been informed of this, could you now express which proposals you support on the guidance talk page. Xandar 00:54, 25 August 2009 (UTC)

Speed of Light and NIST

I still disagree with your reading of [2]. The document says: "a new definition of the metre has been envisaged in various forms all of which have the effect of giving the speed of light an exact value [...] these various forms [...] making reference either to the path travelled by light in a specified time interval or to the wavelength of a radiation of measured or specified frequency [...] have been recognized as being equivalent"

That is, they are considering various proposed standards for the metre, all of which would give the speed of light an exact value. It is these proposed standards which they state are equivalent to each other.

Note that the pre-1983 definition, which is in terms of wavelengths of radiation from a specified natural source, does not fall into the categories listed as equivalent (because it is not of a measured or specified frequency).

Lastly, the document notes that the new definition has the effect of "giving the speed of light an exact value, equal to the recommended value" - in order for the definitional change to have such an effect it must not be not exactly equivalent to the old. EdwardLockhart (talk) 15:03, 27 August 2009 (UTC)

Yes. I take your point, the frequency of the krypton source could not be measured in 1960, so this radiation could not be referred to as having a measured frequency. Whether you could say its frequency was 'specified' is perhaps debatable, its value in Hz was could not be determined but it still had a fixed value. My point is that the atomic transition defines the frequency of the emitted light and the wavelength is determined by the speed of light. In other words the 1960 standard is the exactly distance travelled by light in a fixed time, but in 1960 that time was not known in seconds.

I accept that with the 1983 definition there are two sources of uncertainty in realization of the metre, one is that of measuring the frequency of the light used and the other of delineating the metre using this light. The point that Brews does not seem to get is that all these problems relate to uncertainty in the realization of the metre and do not stop the speed of light from being exact. Martin Hogbin (talk) 09:12, 28 August 2009 (UTC)

You make a good point about the time not being known in seconds. The point of Brews' that I was agreeing with was this - suppose we have someone who learns the following facts in order:

1. The definition of the second
2. The definition of the metre
3. The speed of light in m/s

Then with the pre-1983 definitions, this person is able to make the following deductions about the results of measurements at each stage:

1. The frequency of some Caesium radiation
2. The wavelength of some Krypton radiation
3. The wavelength of (1), the frequency of (2)

But with the post-1983 definitions, they can only make the following deductions:

1. The frequency of some Caesium radiation
2. The wavelength of (1)
3. None

In this restricted and largely useless sense, a pre-1983 statement of the speed of light has more physical information embedded in it.

To put it another way. Suppose we substitute the SI definition of the metre into the statement "the speed of light is 299792458 m/s". Pre-1983, we get:

• The speed of light is N krypton wavelengths per second.

Post 1983:

• The speed of light is 1 lightsecond per second.

Translating into natural units, we get:

• 1 = N . krypton wavelength => krypton wavelength = 1/N

vs:

• 1 = 1

So again, there is physical content in the pre-1983 statement that is not present in the post-1983 statement. It's not especially interesting content, but it is there.

I don't claim that this is an important or interesting fact, but I do think that in attempting to engage constructively with Brews, It would be best to acknowledge his correct statements as well as criticise his incorrect ones. Conceivably this might help him see the errors in his reasoning (on which subject I think we are in exact agreement). Of course, I would quite understand if you thought an attempt at constructive engagement on this point was a waste of time though! EdwardLockhart (talk) 10:02, 28 August 2009 (UTC)

OK, you are welcome to argue with Brews any way you want and I will keep out of the argument. I think it would be better to move all discussion of this topic to the page that I have set up in my talk space, the article talk page really does not need it. I am refusing to argue about the physics on the article talk page now and I think other editors should do the same. Martin Hogbin (talk) 16:25, 28 August 2009 (UTC)

EdwardLockhart: As you can see, not only does Martin refuse to argue with me, but he refuses to take up the points you make as well. Of course a fringe count is a length measurement, completely separate from a time-of-transit measurement, and therefore the pre-1983 definition has more in it than the post-1983 definition. That is the whole point that Martin will not admit, either because he hates to backtrack on his espoused views, or because the logic of this just does not sink in. I have no idea how Martin squares a need to measure a value of c of approximately 299 792 458 m/s before 1983 with a defined value of c of exactly 299 792 458 m/s post-1983 that no longer need be measured. It does appear that historically there is evidence for greater and greater accuracy in c over time, but apparently today we have it nailed. Of course, that is not true, and the enshrined value 299 792 458 m/s has nothing to do with the exact speed of light in a physical sense. Instead, it has to do with replacing length comparisons in terms of fringe-counts with times-of-transit, making length superfluous in the SI system. Brews ohare (talk) 16:36, 28 August 2009 (UTC)

Brews, I will be happy to go through these points in the page in my talk space if it is of interest to you. Martin Hogbin (talk) 16:43, 28 August 2009 (UTC)

So far as I can see, you have stopped contributing to User_talk:Martin_Hogbin/Speed_of_light_set_by_definition. Brews ohare (talk) 16:46, 28 August 2009 (UTC)

Sorry if I have not responded as quickly as you would like but sometimes I do have other things to do. I will respond later. Martin Hogbin (talk) 16:49, 28 August 2009 (UTC)

The section on the luminiferous aether

Martin, The section on the luminiferous aether that Tim Shuba removed, had not, as you have just claimed, been hi-jacked by crackpot science. This claim all comes down to your opinion on Maxwell's 1861 paper, which is clearly an aspect of history which you prefer not to be reminded of. There is nothing crackpot about it. Maxwell demonstrated how the experimental measurements of the electromagnetic/electrostatic ratio leads to a wave equation with the speed of light. It is an aspect of the speed of light which is not related to direct measurements of that speed. I agree with your objections to Tim Shuba's removal of that material, but try to avoid referring to Maxwell's work as crackpottery. David Tombe (talk) 14:12, 29 August 2009 (UTC)

Tim's removal of the section has saved me from needing to have this discussion, for which I thank him. Martin Hogbin (talk) 14:22, 29 August 2009 (UTC)

Martin, You are taking advantage of a biased page ban. The content material of that section was entirely appropriate because it dealt with the most important aspect in the entire history of the speed of light. That is of course the convergence of the measured speed of light by Fizeau and the linkage to the electromagnetic/electrostatic ratio through the experiment in 1856 by Wilhelm Eduard Weber and Rudolf Kohlrausch. What possible motive could you possibly have for wanting to hide this important piece of history from the history section? It's repercussions were still around even when I was teaching physics. It's only since the 1983 re-definition of the metre that it all seems to have been swept under the carpet. David Tombe (talk) 17:10, 29 August 2009 (UTC)

I am not taking advantage of anything because I have not deleted anything from the article. Martin Hogbin (talk) 17:39, 29 August 2009 (UTC)

Martin, you are simply ducking engagement by using a pretext. It would be more appropriate for you to sort the history out and put in a proper development. Supporting Tim Shuba as a convenient way to avoid dealing with the history is not laudable. Brews ohare (talk) 19:00, 29 August 2009 (UTC)

Removal of sourced subsection without comment or discussion

Martin: You removed the following entire sourced subsection of speed of light without comment or discussion, even though it was rewritten to emphasize its relevance and to avoid any comments that might be considered as WP:SYNTH or WP:OR:

Defined speed of light and lengths as times-of-transit

The 1983 definition of the metre introduced the SI units speed of light c₀ = 299 792 458 m/s as a defined (not measured) value. Setting the speed of light to a defined numerical value in the SI units means comparisons of length become equivalent to comparisons of transit times of light.

This equivalence is established by thinking of measurement as a comparison between the quantity being measured and the standard unit; it is a matter of ratios. Mathematically, comparison of two lengths ℓ₁, ℓ₂ with times-of-transit of light, t₁, t₂ may be expressed as the ratio

${\frac {\ell _{1}}{\ell _{2}}}={\frac {c\ t_{1}}{c\ t_{2}}}={\frac {t_{1}}{t_{2}}},$

which is independent of the speed of light c, so long as the same speed of light is realized while measuring both times-of-transit.

As an example, if the time t₂ in the above equation is selected as t₂ = 1/299,792,458 s, and the measurement is done in "vacuum", then ℓ₁ is determined in metres. Thus, choosing ℓ₂ as one metre, the above equation is simply

$\ell _{1}={\frac {t_{1}}{t_{2}}}\ell _{2}={\frac {\ell _{2}}{t_{2}}}t_{1}={\frac {1~\mathrm {m} }{1/299,792,458~\mathrm {s} }}t_{1}=299,792,458~\mathrm {m/s} \times t_{1},$

which recovers the fundamental definition of length provided by the BIPM. This result shows that the determination of ℓ₁ in units of metres is determined completely by the standard time interval selected for the metre, namely 1/299,792,458 s . It also establishes that the use of a transit time of 1/299,792,458 s to define the metre is equivalent to defining the conversion factor between time and length as 299,792,458 m/s.

In-line references

Overview of deleted article

Specifically, to outline the status of each paragraph:

1. Paragraph 1 is simply a preamble to introduce the subsection and makes the point that comparisons of transit time replace comparisons of length. This point is supported by two published sources that say exactly that. They are quoted verbatim in the footnotes. Brews ohare (talk) 22:45, 4 September 2009 (UTC)
2. Paragraph 2 introduces the notion of length comparison via ratios, supported by another source.
3. Paragraph 3 simpy evaluates the ratio expression to show it produces the BIPM definition, which also is sourced.

That is all there is here, IMO. The entire purpose is to discuss clearly the tight connection between a defined "speed-of-light" and the use of transit times for length in the SI system of units. Judging from the Talk page, this is a topic that needs some elaboration. Would you be so kind as to provide specifics as to why you deleted this material in its entirety, without comment or even an Editorial Summary, labeling it as m for minor? Can you identify some statement or wording (that is, something beyond broad generalities) in this sourced material that you find does not meet WP guidelines? Perhaps it can be fixed without a need for total reversion without comment? Brews ohare (talk) 22:45, 4 September 2009 (UTC)

Brews, it should be clear to you that your misconceptions on this subject are not required on 'Speed of light' article. Several editors have told you this and have deleted them from the article. You have abandoned our discussion the subject on the page that I set up for the purpose. Not only will I continue to delete your own personal and inaccurate views on this subject but I will suggest that other editors do the same. Martin Hogbin (talk) 08:56, 5 September 2009 (UTC)

Martin: I am happy to correct my misconceptions, but you have not pointed out to me what is objectionable in the above submission. I think it is plain vanilla and completely sourced. Please tell me specifically, verbatim, what is there that seems to you mistaken. At the moment, I feel your reaction is unrelated to this particular submission. Brews ohare (talk) 12:54, 5 September 2009 (UTC)

Arbitration Request:Speed of light

NOTICE: Upon the request of Brews ohare and Abtract, you have been added as an involved party in Wikipedia:Arbitration/Requests/Case#Speed of light. —Finell (Talk) 02:27, 7 September 2009 (UTC)

Thanks for letting me know. 86.142.238.242 (talk) 11:03, 7 September 2009 (UTC)

Wikipedia:Arbitration/Requests/Case/Speed of light

An Arbitration case involving you has been opened, and is located here. Please add any evidence you may wish the Arbitrators to consider to the evidence sub-page, Wikipedia:Arbitration/Requests/Case/Speed of light/Evidence. Please submit your evidence within one week, if possible. You may also contribute to the case on the workshop sub-page, Wikipedia:Arbitration/Requests/Case/Speed of light/Workshop.

On behalf of the Arbitration Committee, Hersfold ^(t/a/c) 03:59, 9 September 2009 (UTC)

Speed of light arbitration evidence

In accord with the edit notice ([3]), a portion of your evidence submission has been moved to the talk page.[4][5] None of the information has been deleted. Everything moved from the main evidence page is entirely preserved on the talk page. It is possible that the moved portion may require more supporting links to be appropriate for evidence or that the portion moved is simply more commentary than evidence. Please review the moved portion to decide if it needs revision as an evidence submission or if it should remain on the talk page as commentary. If you feel that this contribution was moved in error, please feel free to contact me to discuss the matter. Thank you for your understanding. Vassyana (talk) 07:47, 13 September 2009 (UTC)

Semenya

The cats out of the bag, Martin, and all the sources are moving ahead without us. Please reach some compromise or give up blocking mention of the results of the tests. You can't keep this up forever, and we need your influence to ensure that it is properly done. Chrisrus (talk) 18:06, 13 September 2009 (UTC)

Are you saying that the results of some tests have been published. Which tests and where were they published? Martin Hogbin (talk) 19:19, 13 September 2009 (UTC)

I meant in the news. What kind of publishing are you waiting for? Chrisrus (talk) 19:39, 13 September 2009 (UTC)

Sorry but which news? TV radio, when and where? Martin Hogbin (talk) 19:41, 13 September 2009 (UTC)

Turn on the radio, or Google News it, or whatever. Don't you get the paper? Chrisrus (talk) 20:05, 13 September 2009 (UTC)

I have not seen or head the news today. I can find nothing new on Google news. Could you give me a link please. Martin Hogbin (talk) 20:16, 13 September 2009 (UTC)

http://news.google.com/news/search?aq=f&pz=1&ned=us&hl=en&q=semenya

http://www.dailytelegraph.com.au/sport/semenya-has-no-womb-or-ovaries/story-e6frexni-1225771672245

I thought you were referring to news! That is all old hat. I will continue on the article talk page. Martin Hogbin (talk) 20:37, 13 September 2009 (UTC)

I'd rather you responded to JFQ than me, if it's all the same to you. Chrisrus (talk) 20:44, 13 September 2009 (UTC)

I had already written my response to you before I read this but I have left a response to JFQ's statement. Martin Hogbin (talk) 20:51, 13 September 2009 (UTC)

Arbitration

Given you change of opinion as to the appropriate remedy for Brews, I suggest, for the sake of clarity, that you (1) mark your present proposed remedy as struck out (but don't delete it) and (2) add a new proposed remedy, underneath the discussion, of a topic ban for Brews. Finell (Talk) 23:40, 6 October 2009 (UTC)

Done. Martin Hogbin (talk) 08:59, 7 October 2009 (UTC)

Wikipedia:Arbitration/Requests/Case/Speed of light

This arbitration case has been closed, and the final decision may be viewed at the link above.

• All editors are reminded to be civil at all times and seek consensus where possible, and encouraged pursue dispute resolution when necessary.
• Brews ohare (talk · contribs) is warned for his conduct in this dispute, and placed under a general probation for one year, under which any uninvolved administrator may impose sanctions if Brews ohare fails to adhere to the purpose of Wikipedia or general editing and behavioral guidelines, policies, and expectations, despite warnings.
• David Tombe (talk · contribs) is also warned for his conduct in this dispute and during the course of the arbitration case, and is placed under the same general probation but for an indefinite duration. David Tombe may not appeal his probation for one year, and is limited to one appeal every six months thereafter.
• Both Brews ohare and David Tombe are banned from all physics-related pages and topics, broadly construed, for twelve months.
• Violations of the topic bans or general sanctions may be enforced by blocks of up to a week in length for repeated violations, to increase to one year after the third block. All blocks and other sanctions applied should be logged on the case page here.

For the Arbitration Committee, Hersfold ^(t/a/c) 22:28, 20 October 2009 (UTC)

Discuss this

edit conflict at Monty Hall talk page

Martin - we edit conflicted at talk:Monty Hall problem. Are you willing to refactor your suggestion into the structure I set up? -- Rick Block (talk) 15:34, 2 December 2009 (UTC)

I will do that Martin Hogbin (talk) 20:30, 2 December 2009 (UTC)

Thanks. -- Rick Block (talk) 01:20, 3 December 2009 (UTC)

t:GW

Welcome to the t:GW snakepit. It seem to me as something of a newcomer that material is being removed from this page - but you don't say what. If you do, I can tell you. A quick look through this talk page shows that practically none of it is directly about improving the article - yes, the talk page is badly ill-disciplined. If you can see a way to improve that, please do. I favour deleting irrelevance and early chopping of sections such as "Article Title incongruent with content" which have no hope of going anywhere to try to keep discussion focussed. I could ahve said all this over there, of course, but it would have got buried William M. Connolley (talk) 12:31, 20 December 2009 (UTC)

I am generally not in favour of removing material from the talk pages at all. As I proposed, if it is desired to keep the talk page clearly focused then as sub page for general discussion is an idea. The problem is that it is hard to separate improving the article from general discussion when the topic of the page is contentious. Martin Hogbin (talk) 12:45, 20 December 2009 (UTC)

I agree - it is a difficult problem. You are suggesting a general "discussion of blah" page and keeping the article talk page itself for specific topics? And people posting generic stuff to the article talk page would have their stuff moved to the sub page? And who would handle the inevitable claims of censorship? William M. Connolley (talk) 12:58, 20 December 2009 (UTC)

Where I have seen it done before, editors were simply asked to continue general discussions to the 'discussions' page. The problem with a strict rule is that it is not possible to agree on how to improve an article if there is no agreement on the subject matter. In that case either the strict 'improving the artcle' rule needs to be relaxed or a separate page set up.

What is with all this archiving sections? Martin Hogbin (talk) 14:21, 20 December 2009 (UTC)

I think that is a non-starter. Most of the trash on the page is by non-focussed contributors who *want* to rant; they aren't going to politely go off to a sub-page where they can rant unnoticed William M. Connolley (talk) 16:01, 20 December 2009 (UTC)

It's all well and good for you to say they're just "ranting;" however, that is an opinion based on criteria which you define, based on opinions which you hold. I agree with Martin; there is extremely thin grounds for removing other editors' comments, based on your personal opinion that they are off-topic. --Steve, Sm8900 (talk)

Draft RFC

Martin - The draft is just that, a draft. It is not appropriate to comment on it yet. -- Rick Block (talk) 00:27, 22 December 2009 (UTC)

It's not draft anymore, see Wikipedia:Requests for comment/Glkanter. You're welcome to add a "Response" or an "Outside view", but you might want to wait until Dicklyon certifies the official RFC (if he doesn't within two days it simply expires quite harmlessly). -- Rick Block (talk) 03:54, 22 December 2009 (UTC)

GW issues

Martin, Just for info part of the problem with GW articles is this. There are three or four GW sock masters who produce on average one new sock a day each with a specific pattern: ten to twenty edits elsewhere and then try to introduce "Global warming is a fraud" type language into the article. It is tiresome and makes everyone a bit short with edit summaries etc. It also makes the discussion tedious because the socks turn up in hordes in some of the discussion, make a lot of personal attacks and allegations etc and when two days later the CU has gone through they repeat with another sock. Few people flicking through the discussions bother to strike sock comments and it gives a distorted view. I didn't look at your talk page comments but anything you could do to help is welcome and I am sorry if you felt you were not welcomed on the page. But introducing new rules has got to allow for this disruption --BozMo talk 07:13, 23 December 2009 (UTC)

Thanks for you offer to help. Let me tell you what caused me to take the action that I did. First let me state clearly that I am a AGW sceptic and I believe that there are two sides to the subject which should be appropriately represented in the article. I do not believe that it is the same as creationism or holocaust denial where there really is only one side to the story. That being said I fully support WP policy of requiring support from reliable sources, especially as this is a FA.

So, I looked at my watchlist and saw an edit, marked as minor and reversion of vandalism. When I looked at the diff, I saw that the material that had been reverted was information on the subject of the article, rather than say 'Climate change scientists are wankers'. It was not particularly well written, it was unencyclopedic and the sourcing may have been dubious, but it was not vandalism. The reversion was also marked as a minor edit, which it clearly was not. In order to draw attention to what I consider rather oppressive and impolite behaviour I, rather rashly, reverted the edit with a short explanation. I was expecting my change to be reverted but that it would cause editors to look at the talk page, where I had given a little more detail on why I had taken the action that I had. After a short discussion on the talk page I was rather rudely told to 'take my whining elsewhere', and the section was deleted. I restored the section with a note that I would start an RfC if the section was removed again. It was so I did. It is a rather silly escalation of what could have been an informal discussion on the talk page but I feel that I was left with no choice. Some regular editors of this article do seem to have a strong feeling of page ownership with ruthless suppression of any dissenting opinion. Had the edit summary said something along the lines of, 'Remove poorly sourced and unencyclopedic material', I would probably have left it. All I am asking for is the normal polite formalities of WP to be followed. The more contentions the topic, the more important this is. Martin Hogbin (talk) 10:23, 23 December 2009 (UTC)

Am back from a break now but still on leave. Ok, I see. In general edits which are believed to be sock edits do get reverted under minor. I agree people should be civil and not tell you to take your whining elsewhere. When I have a minute I will look through the diffs. --BozMo talk 21:18, 27 December 2009 (UTC)

Which RFC? William M. Connolley (talk) 10:35, 23 December 2009 (UTC)

The one I have just started. Martin Hogbin (talk) 10:44, 23 December 2009 (UTC)

Thanks. I found the RFC. Your langauge there is well over the top - ruthless etc. And you give no examples. Are you sure this is as temperate as it should be? William M. Connolley (talk) 10:50, 23 December 2009 (UTC)

See the history above. There are only a couple of diffs which I will add to the RfC but discussion of the subject was deleted from the talk page. Where else do I go? Martin Hogbin (talk) 15:02, 23 December 2009 (UTC)

You need to add some extra diffs - see there. And I rather suspect that you need to have a real problem, this isn't one, or at least it doesn't look like one yet. I still don't understand how you could have though that everyone would be so familiar with this that you didn't need to tell us what it was William M. Connolley (talk) 16:44, 23 December 2009 (UTC)

I have added an explanation at the top of the RfC. Martin Hogbin (talk) 17:14, 23 December 2009 (UTC)

I mean that this [6] complains a missing edit, but you don't say what it is William M. Connolley (talk) 17:29, 23 December 2009 (UTC)

Thanks, I see, I will add that. Martin Hogbin (talk) 17:32, 23 December 2009 (UTC)

Martin Hogbin, I totally agree with your comments regarding the global warming page. —Preceding unsigned comment added by 82.12.240.60 (talk) 22:10, 23 December 2009 (UTC)

Closing Talk:Global warming RfC

I just closed that discussion, as it focuses on your fellow volunteer editors rather than improvements to the article. Please follow the steps outlined in Wikipedia:Dispute resolution in any future similar situations. You appear to be attempting to engage in good faith and I would prefer not to block you, but this family of articles is subject to a fair bit of disruptive editing at the moment. Please be especially careful to keep your discussions on topic per Wikipedia:Talk page guidelines and avoid edit warring in preference to discussion and consensus. Regards, - 2/0 (cont.) 18:21, 25 December 2009 (UTC)

I only wish that I could discuss the issues involved with the Global warming article but I have been blocked at every turn by the regular editors there. I first made a comment on what I believed to be an incorrect edit summary. THis discussion was immediately deleted from the talk page. I restored it and it was deleted again. I therefore started an RfC to get the opinions of other uninvolved editors, as I understand it this a recommended dispute resolution procedure.

You are now proposing to close the RfC before other, uninvolved, editors have had a chance to comment. This is quite wrong in my opinion and contrary to the whole spirit of WP and cooperative editing. Martin Hogbin (talk) 22:40, 26 December 2009 (UTC)

I have something specific to add to GW - it needs a section on dissent. Searching for similar controversise, I checked Evolution - which has a perfectly decent one here, 4 paragraphs and around 10% of the article. (Actually, it's misleadingly titled (Social_and_cultural_responses) but I searched for "Creationis..." andgot there). Now, I feel that the contra-GW case probably needs rather more detail than that in the GW article, given the public interest and serious scientific doubt expressed from at least some respectable sources. Otherwise, the impression given is of severe bias.

I don't know whether I meet the conditions required to put my name to a challenge, I don't recall picketing individual editors on their TalkPages, which may be a requirement. I'm also leery of getting into a monster argument with editors who, as you seem to say, have no hesitation silencing the opposition. Even my request for a list of decisions on rightful conduct was deleted!

Let me add that I come from the opposite pole to most objectors, because I'm pretty much convinced on GW. There's a well thought out Mechanical Engineering report somewhere that assumes pretty steady sea-level rise (1m/century? I forget) until the year 3000, and when I read it, I suspected it to be an understatement. The very best evidence I see for there being flaws in GW is the deletion of comments like yours and mine. MalcolmMcDonald (talk) 09:41, 29 December 2009 (UTC)

I completely agree with you, scientific theories should be able to stand up to continuous scrutiny. I am not sure if a 'dissent' section is the best way forward, I have no strong objection to it, but this is something that could be discussed on the talk page, if only the current regular editors would allow this. I have even suggested a separate 'Discussion' talk page where more general issues concerning the article could be discussed. (This approach has been used on the Monty Hall problem page, for example) This will only work if those supporting the status quo agree to actively discuss issues on the additional page with a view to longer term changes to the article. The current talk page can be used for discussion of short term and medium term article changes. If the regulars treat the new page as an 'idiots playground' no one will post there and it will be pointless. Posting on the new page must be voluntary, the best way to get editors to use it is for to respond to what they see as disruptive material on the main talk page with something along the lines of "I will reply to the issues you have raised on the 'Discussion' page". Material should only be deleted or moved by the original editor. Martin Hogbin (talk) 10:51, 29 December 2009 (UTC)

Formal mediation

Martin - Are you working on a formal mediation request for MHP? An informal mediator has dropped by and is willing to try to help. I think we should do one or the other of these. -- Rick Block (talk) 18:55, 27 December 2009 (UTC)

No, I have done nothing but I am happy to try either. Martin Hogbin (talk) 21:07, 27 December 2009 (UTC)

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Your position

I'm not happy with this part of your position statement in the MHP:

The simple solution section should be followed by an explanation of why some formulations of the problem require the use of conditional probability, with reference to the paper by Morgan et al. and other sources. It should also include the various variations of the basic problem and other, more complex, issues.

I got the idea you had seen the light in the mean time (or was its speed yet too high for you). This part suggests you think of a formulation of the MHP that doesn't require conditional probability. I would very much appreciate you telling me which formulation you have in mind. Nijdam (talk) 23:52, 29 December 2009 (UTC)

How about You will be offered the choice of three doors, and after you chose the host will open a different door, revealing a goat. What is the probability that you win if your strategy is to switch. Which none other than the great Morgan et al. themselves call the unconditional problem. Martin Hogbin (talk) 00:00, 30 December 2009 (UTC)

This is deciding whether or not to switch before the host opens the door (right?). Do you really consider this to be a version of the MHP? -- Rick Block (talk) 01:19, 30 December 2009 (UTC)

Do you? Nijdam (talk) 09:04, 30 December 2009 (UTC)

Yes, of course it is. As I say on my dissenters talk page it is most likely what Whitaker actually wanted to know. You need to consider his question in its proper context. He was not a student of probability posing a question at a lecture he was a member of the general public (or a figment of the editor's imagination) posing a question to a popular general interest magazine. All he probably wanted to know was if was better strategy to switch or stick on a game show. There is no indication in his question that he thinks it is important to consider his choice after the door has been opened.

You may not agree that this is likely meaning of the question but you must surely agree that it is a formulation of the problem. There is nothing worse in my book than being half pedantic. If you are going to insist that we mention the issue of which door the host opens, even when it clearly makes no difference to the answer, then we must also mention that this applies only to some formulations of the problem. Martin Hogbin (talk) 09:54, 30 December 2009 (UTC)

arbitration notification

You are involved in a recently-filed request for arbitration. Please review the request at Wikipedia:Requests for arbitration#Climate Change and, if you wish to do so, enter your statement and any other material you wish to submit to the Arbitration Committee. Additionally, the following resources may be of use—

• Wikipedia:Requests for arbitration#Requesting Arbitration;
• Wikipedia:Arbitration guide.

Thanks, Please comment at the arbitration case or on my talk page- I'm notifying a large batch of editors. tedder (talk) 02:36, 30 December 2009 (UTC)

New discussion at the Pete Townshend page

Would you like to join it? Pkeets (talk) 00:49, 31 December 2009 (UTC)

Missing my point

The correct place to discuss that is with the editor who removed the comment, not on the article's talk page. Adding an off-topic section to discuss the removal of off-topic comments just makes matters worse. Use the editor's user talk page. Thanks. Guettarda (talk) 18:01, 8 January 2010 (UTC)

Thanks for your 'advice'. The problem that I have is that I am unlikely to get any sensible response from the tag-team member who removed my comment. In order to get anything done, I need to attract the attention of other editors. There clearly is a band of editors exerting total control over this page. Martin Hogbin (talk) 18:26, 8 January 2010 (UTC)

Again?

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And another. HJMitchell You rang? 19:22, 8 January 2010 (UTC)

Global warming

Thank you for your contributions to the encyclopedia! In case you are not already aware, an article to which you have recently contributed, Global warming, is on article probation. A detailed description of the terms of article probation may be found at Wikipedia:General sanctions/Climate change probation. Also note that the terms of some article probations extend to related articles and their associated talk pages.

The above is a templated message. Please accept it as a routine friendly notice, not as a claim that there is any problem with your edits. Thank you. --TS 13:01, 9 January 2010 (UTC)

Dear Martin,

Ref [7] please note that asking for an explanation of a revert is completely acceptable and should be done on talk. However undoing a revert whilst asking for an explanation, on an article on probation, in my view is edit warring. There is a fine line in an edit war as each side inches a little further forward and there is a degree of arbitrariness on when the line is crossed which is why I am dropping you a note rather than taking action. I am sure that you wish to contribute constructively to this article: please do not edit war. --BozMo talk 07:40, 11 January 2010 (UTC)

Thank you for your advice. I am not sure that a single revert could be classed as edit warring. Regarding article probation, this requires all editors to act to the highest standards. Reverting a good faith addition (even if inaccurate) with no edit summary and with the change being marked as minor is also not acceptable, especially on an article on probation, and I was bringing this to the attention of all editors as this type of activity seems to be endemic on the GW article. I have mentioned this before on the talk page, only to have my comments deleted. To contact each editor in turn to make the point is not practical.

I accept that my action was a little over zealous but, had the reversion had a short edit summary saying something along the lines of, 'Text not supported by cited source', then I, or any other interested editor, could have checked my facts before reverting. The editor concerned has apologised and that is the end of the matter as far as I am concerned. Let us hope that everyone has learned a lesson. Martin Hogbin (talk) 10:07, 11 January 2010 (UTC)

I don't think this [8] can be regarded as a good-faith addition. Sourcing something clearly controversial to the Daily Mail is not acceptable, even if the material is good, which in this case it wasn't. In 2010, some of the world's most eminent climate scientists said is nonsense. Martin: if you really know the GW topic so badly that you can't recognise this text as obviously unacceptable, then you should make a habit of discussing your proposed edits on talk *first* rather than reverting them back in William M. Connolley (talk) 10:19, 11 January 2010 (UTC)

The text may have been unacceptable and should have been reverted, but not without without comment. A terse edit summary would have done the job. Martin Hogbin (talk) 13:14, 11 January 2010 (UTC)

@Martin. That's fine, I am sure you realised I also complained to CC about the lack of edit summary at the same time but I am not sure that I accept the original edit which you reverted back in was good faith; aside it itself being done under "minor" with content which Dalej78 must have realise would be unacceptable, I have been through the last couple of years of Dalej78's edits and it is unclear to me that there have been any positive contributions at all since 2007, just deliberate attempts to undermine the atmosphere. I think the Dalej78 account as it stands would qualify for indef blocking as vandal only. Therefore although I do not doubt your good faith, someone reverting Dalej78 as a minor edit without comment was also understandable. --BozMo talk 10:49, 11 January 2010 (UTC)

I do understand the frustration felt by the regular editors of a FA when poor quality material should be added. I also agree that, in many cases, immediate reversion is appropriate, but in the case of a highly contentions topic like this, that is also under probation, there is an onus on both sides to act properly. As I said above, a terse edit summary would have allowed interested editors to check the facts. In the current climate (no pun intended) this should be the expectation for all edits except genuine minor ones (typos etc).

I cannot accept that Dalej78 is a vandal just because his edits do not meet the standards required for an FA. He is clearly trying to balance the article by adding to the 'Debate and scepticism' section. He may be making a bad job of this, but that is not vandalism. Martin Hogbin (talk) 13:14, 11 January 2010 (UTC)

Your edit to List of scientists

Whilst I don't disagree or agree with your edit this page has had a lot of wrangling over the text and most changes are discussed on the talkpage, so don't be surprised if it is undone. I do disagree with your edit summary. The page is not a list of 'climate scientists' who oppose the mainstream view, it is a list of 'scientists'. If we had a list of climate scientists first of all it would be difficult to define and secondly we might actually find it difficult to find enough who fit the criteria for a list. Therefore majority does not really properly address this, "vast overwhelming majority" might but then those are words we tend not to use on wikipedia. Polargeo (talk) 16:34, 11 January 2010 (UTC)

I understand what you are saying but the article made no sense as it was. I am sure that there are some climat scientists who disagree, so to start with 'climate scientists agree' is nonsense. The first section, and indeed most of the text seems to be promoting what it is that the list of scientists disagrees with. Martin Hogbin (talk) 17:38, 11 January 2010 (UTC)

Monty Hall problem mediation

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Mediation is getting underway. Do you have Wikipedia:Requests for mediation/Monty Hall problem on your watch list? -- Rick Block (talk) 14:37, 5 February 2010 (UTC)

Thanks, I will add it. Martin Hogbin (talk) 22:34, 5 February 2010 (UTC)

Why is there such friction at GW?

Hi Martin. I worry that part of the problem at Global Warming is that there are many ways to change the article but only one way for it to stay the same. I wonder if it would be worth listing the different views on what direction the article should be taking. eg

(The "Improvement "Chart" removed from here and placed at my TalkPage here). MalcolmMcDonald (talk) 08:25, 24 January 2010 (UTC)

In my experience attempts to organise the improvement of a page rarely succeed. Some editors will not participate in your scheme, others will start up their own schemes.

In my opinion the most important problem on the GW page is that of oppressive editing and page ownership, especially the rapid deletion and archiving of discussion. Once these issues are resolved it might be easier to move forward. Martin Hogbin (talk) 15:34, 23 January 2010 (UTC)

There is a massive problem of page ownership and oppressive editing and it's obvious to a lot of people. TalkPage deletions of other people's comments and rapid archiving are a big part of it. I wondered if a table might highlight the fact there were about 6 editors rejecting all suggestions for improvement, and up to 20 who have changes they'd like to make. The stone-walling we see damages the cooperation that many other editors long to embrace. MalcolmMcDonald (talk) 16:02, 23 January 2010 (UTC)

I think you would find that any attempt to poll editors in the way that you suggest will be rapidly sabotaged. By all means give it a try. Martin Hogbin (talk) 16:28, 23 January 2010 (UTC)

How do you feel about hosting it on your page? I could lift the whole thing and put it on mine, were mine not sullied by very respected but angry-looking experts making accusations that "of course the article is fit for purpose, how dare you suggest otherwise".

In the not too-distant future, some editors might face demands "if your name is not linked to a view on Martin's page it must be because you're fringe and progress here will continue without you". Two can play at the game "you're not main-stream, therefore we can ignore you". MalcolmMcDonald (talk) 16:45, 23 January 2010 (UTC)

I think your page would be better. It is your idea. Martin Hogbin (talk) 17:14, 23 January 2010 (UTC)

Do you feel that any of the options fully reflect your current position and would you be willing to enter your name, and a synopsis of your position, in the appropriate place? MalcolmMcDonald (talk) 17:24, 23 January 2010 (UTC)

I would be happy to add my name. I think one section should read 'Censorship currently makes cooperative editing and improvement possible'. This is the key issue to me. Also maybe 'the section on debate and skepticism should reflect the views of sceptics' Martin Hogbin (talk) 17:50, 23 January 2010 (UTC)

There we are, make any other suggestions and I'll take it away. MalcolmMcDonald (talk) 20:23, 23 January 2010 (UTC)

It is all yours. Now we need to get the views of other editors. Martin Hogbin (talk) 20:32, 23 January 2010 (UTC)

I imagine this being a slow-burning project and I'm contacting critics of the article first. If I can get a reasonable turn-out (perhaps 20 or so) then I can list and/or request that supporters of the current article show their hand. All suggestions gratefully recieved. MalcolmMcDonald (talk) 16:26, 24 January 2010 (UTC)

Perhaps you should formulate this as a RFC. Contacting critics of the article first seems like a poor choice of strategy. Surely the opinions of the uninvolved would be more useful. --TS 16:51, 24 January 2010 (UTC)

If you wish to help with this important project, you'd be very welcome. You could start by adding your name to the "basically going OK" category, with any caveats you have. MalcolmMcDonald (talk) 17:45, 24 January 2010 (UTC)

You have been requested by Awickert (talk) to provide examples here of "GW article reads like an advertisement". MalcolmMcDonald (talk) 19:14, 25 January 2010 (UTC)

ANI

There is an issue being discussed at WP:ANI#Deleting and readding of talk page comments in which you may be involved.--Jojhutton (talk) 21:30, 23 January 2010 (UTC)

"I didn't hear that"

As I remarked to MalcolmMcdonald on a separate subject:

You're becoming a stuck record, ignoring the clearly stated comments of other editors and coming back again and again to the same rejected suggestions, like an old fashioned gramophone whose needle has stuck in part of the record, replaying the same section of music repeatedly.

You've asked the same question repeatedly on talk:global warming: [9] [10] [11]. The answer to this question, you've been told, is complex, yet you repeat the question demanding an answer. This seems unrelated to improving the article (and thus the potential problem here is more egregrious than in MalcolmMcDonald's case).

There are appropriate forums and blogs in which you could pose this question and argue over the reponses. Wikipedia is not one of them.

Please clarify how you see this line of questioning improving the article, and stop simply parroting the same question. --TS 16:48, 24 January 2010 (UTC)

Thank you for your kind remarks. I have covered the issues that you have raised on the article talk page. Martin Hogbin (talk) 17:40, 24 January 2010 (UTC)

I have repeatedly made real and detailed suggestions to improve the Global Warming article, my own particular gripe (backed by numerous examples) being that the article fails to be informative. I've yet to come across examples where the article could be descibed as informative. For this I suffer personal attack.

Other people have other serious gripes about the article, eg "Include politics of GW", "the views of sceptics are not represented properly", "Censorship makes cooperative editing and improvement extremely difficult" and "Article reads like an advertisement". I don't understand why it's such a problem to write this article to be useful to readers. MalcolmMcDonald (talk) 17:42, 24 January 2010 (UTC)

Indeed. Conformance to the Copenhagen Accord must have had some expected gain in GW terms. It would be useful and informative if the article were to state a value for this. What is the problem with doing so. Martin Hogbin (talk) 17:47, 24 January 2010 (UTC)

The whole point of this article or suite of articles is (presumably) to make information easily accessible. Instead of which, it sometimes appears that the article is being made as un-helpful as possible. Sorry to bang on about things, but "Amazon" and "desertification" have been taken out - how can that be helpful? No mention of the Antarctic - an astonishing omission! If people can't answer questions on TalkPages, then it becomes doubtful they can write articles that answer questions either. MalcolmMcDonald (talk) 18:02, 24 January 2010 (UTC)

Malcolm you are confusing "not anwering" with "not knowing". Wikipedia policy does not allow for talk-pages to become a question&answer forum. We are "refusing to answer" questions that is not going to improve the article. You have to turn to blogs or other forums to get answers to your questions. We are also not here to seek the WP:TRUTH, but instead to describe the subject, as seen from science.

Some of your questions btw. are answered on Wikipedia, but they are answered on sub-articles, since every topic cannot be discussed at the top-level article.

Glaciers are described in Retreat of glaciers since 1850. IPCC ARII criticism is covered in Criticism of the IPCC AR4. Antarctica in Climate of Antarctica (amongst others), Coral bleaching in Coral bleaching, Arctic shrinkage in Arctic shrinkage, .....

There are so many different sub-topics that are related to global warming, that the top-level article only summarizes some articles, which again may have summaries of several other articles. At each step details are lost, that is not from ignorance, but from necessity. --Kim D. Petersen (talk) 18:18, 24 January 2010 (UTC)

I see people not being helpful in direct interaction and it immediately explains what I and so many others have noticed, the product of this labour is almost completely unhelpful. I've proved that so often, from so many angles, that I'm getting sick of repeating myself.

Then I make suggestions to improve the article and I'm told off for "advocating". I cannot deny it. I advocate that the article should inform its readers/provide answers to their questions. MalcolmMcDonald (talk) 19:09, 24 January 2010 (UTC)

There is no rule against collecting opinion from already involved editors. Martin Hogbin (talk) 21:00, 24 January 2010 (UTC)

Good, I didn't think there should be. But I need to do a list of all the people to ask. MalcolmMcDonald (talk) 21:34, 24 January 2010 (UTC)

The trouble is, from what i can detect, that your defintion of how the article would be "usefull" isn't encyclopedic. An encyclopedia "attacks" a topic/subject from a standpoint significantly more like a text-book, than a Q&A/Debunking angle. We are here to describe what science says about the subject, and from the balance/view that scientists consider important. What you seem to be looking for is something that can answer your questions about the current news-cycle on global warming, and for that you need to go to other sources. --Kim D. Petersen (talk) 21:47, 24 January 2010 (UTC)

The article is entitled 'Global warming' not 'The science of global warming'. It should therefore cover the whole subject, including, science, causes, effects, mitigation, adaptation, and politics. The mitigation action of states, for example, is not controlled by science but by a mixture of science and politics. Martin Hogbin (talk) 00:31, 25 January 2010 (UTC)

I always thought an encyclopedia was written to answer questions, to solve arguments, to inform. I never realised that articles were intended to teach along the line of text-books. In fact, I wonder where that comes from. MalcolmMcDonald (talk) 08:16, 25 January 2010 (UTC)

@ Martin Hogbin - making some other changes, I've taken out the part where you said the chart is for the GW article only. Though you may have a clearer idea on this than me and be right. MalcolmMcDonald (talk) 12:56, 26 January 2010 (UTC)

It is your chart, so I guess that I should have left you to answer the question. Might I suggest that you create a special page in your user space for the table. Martin Hogbin (talk) 12:58, 26 January 2010 (UTC)

Thanks

For [12]. I was probably silly not to start a new section. BTW I think it was Boris not TS who complained (but I think it is fine, and if you do kind of break any rules along the lines of "now we know what we want lets russle up a lynch party" I will try to discuss it with you first). --BozMo talk 13:35, 26 January 2010 (UTC)

That's right. My comments were that it might be better as a RFC and instead of involved parties (for and against the global warming article in its present form) it might be more helpful to seek opinions from those uninvolved. --TS 14:15, 26 January 2010 (UTC)

The Improvement Chart is a work in progress to try and discover what changes have widespread support amongst people who've tried to make other improvements. MalcolmMcDonald (talk) 14:43, 26 January 2010 (UTC)

Have you tried analyzing how the successful improvements in the article actually take place? By examining these and comparing with those that have been proposed but failed, you might get a good handle on how to make successful proposals. --TS 14:59, 26 January 2010 (UTC)

I know how "improvments" are done. Just when a discussion on the value of key-words is attempted (maybe they're the single most important and valuable aid to readers navigating for specific information/references?) and shortly after we were told we're stupid for not doing this already, vested editors come along and further reduce the small number of key-words in the article. That happened during a process where there were editors trying to stop the censorship.

WP:PRESERVE states "Try to preserve useful content. As long as any of the facts or ideas added to the article would belong in a "finished" article, they should be retained and the writing tagged if necessary, or cleaned up on the spot". Care to guess how that works in practice? MalcolmMcDonald (talk) 15:16, 26 January 2010 (UTC)

TS, I do not need to make proposals. This is Wikipedia - the encyclopedia that anyone can edit. Please tell me why you would not want key data on AGW mitigation to be in the article. Martin Hogbin (talk) 17:09, 26 January 2010 (UTC)

Can I possibly plea for the article to be shorter not longer? BTW there are fixes on the key words which work for search engines using section redirects (create an article with the name you think the search should win and e.g. Freaking Hawking put in something like #REDIRECT [[Stephen Hawking#Appearance on the Simpsons]] of course we need to decide whom we wish to send where, and a lot of admins get tetchy about articles created to redirect but you don't have to mention the key word to get the query whereever you want, and if you do it with a bit of discussion first it should survive trial by fire. --BozMo talk 21:31, 26 January 2010 (UTC)

Are you sure this on the right page, I have no idea what you are talking about. Martin Hogbin (talk) 22:08, 26 January 2010 (UTC)

Sorry mainly it was at Malcolm ref the comment above on keywords. Agree I will tell him somewhere else sometime. --BozMo talk 22:12, 26 January 2010 (UTC)

I'd be very interested to hear from you on this subject. But my proposal does not concern raising the article in Google ratings, but including key-words in each article (eg "Amazon" and "Antarctic", puzzlingly missing from the main Global Warming article) with links leading to sub-articles containing the detail. It's not difficult to get to the articles, it's the difficulty of navigating them that is so frustrating. As we were told, Good grief, how much spoon-feeding do you need?, we're meant to navigate by "search" on words within articles. Unfortunately, this won't work unless we facilitate it by providing the "key-words" people will tend to use. MalcolmMcDonald (talk) 15:48, 29 January 2010 (UTC)

Please note

From WP:BAN: A banned user who evades a ban, may have all of their edits reverted without question. Short Brigade Harvester Boris (talk) 11:57, 28 January 2010 (UTC)

Thanks

Sorry that no one wanted to discuss what you had to say on talk:Global warming. But thank you so much for showing the good faith and trying to start a new section on content. So it goes :( Awickert (talk) 03:26, 8 February 2010 (UTC)

Request for Amendment to Arbitration

Hello, Martin Hogbin. This is to inform you that there is a request for amendement regarding an arbitration case that you have commented on.Likebox (talk) 05:03, 8

Standing in the way of a productive mediation

You seem to be spending more time criticizing me or your opposing parties than contributing to a productive mediation. Furthermore I urge you to be open-minded as to the real-time option which has "unstuck" many intractable mediations in the past; your statement that you "will not accept mediation through those media" is obstructionist and unhelpful. Andrevan@ 21:03, 15 February 2010 (UTC)

I have not criticized you or those you call my opposing parties. You asked (referring to IRC) , 'Does everyone feel comfortable with that sort of approach?'. I have replied that I am not. Martin Hogbin (talk) 22:44, 15 February 2010 (UTC)

Modification of Brews' sanctions

Thanks for your generous support in modification of my sanctions. Unfortunately, and for no stated reasons, no change is likely. I am sorry that no assessment of the suggestions and evidence was made. Brews ohare (talk) 19:22, 16 February 2010 (UTC)

It seemed only fair to me that you should be able to express your own opinion in your own user space. Martin Hogbin (talk) 19:32, 16 February 2010 (UTC)

Your RFC suggestion

Your RFC suggestion is a good one, to say to Pedant17, "Come clean and admit you are using E-prime, explain why you thing it is appropriate to this page, and try to get a consensus to use it. If you do not get a consensus to use E-prime throughout, you can expect your edits to be rapidly reverted". I think that as you are the one that suggested this idea, perhaps you could leave that comment/suggestion at his talk page? Thank you for your time, Cirt (talk) 16:32, 20 February 2010 (UTC)

The problem is that Pedant17's motivation does not seem so clear cut to me. Martin Hogbin (talk) 00:09, 21 February 2010 (UTC)

Hrm, it was not I that came to the assessment that Pedant17 was motivated by E-Prime, but multiple different editors previously-uninvolved with this particular article, and I agree with them. Cirt (talk) 06:06, 21 February 2010 (UTC)

Paywall source?

Regarding this request: I've sent you an email. I'll see if I can locate an online transcript of the Feynman lecture. Gabbe (talk) 17:23, 16 March 2010 (UTC)

Thanks. Martin Hogbin (talk) 17:37, 16 March 2010 (UTC)

RfC on Talk:Nahum Shahaf

Thanks for your sugestion, I'm sorry an editor dismissed it so flippantly. I would hope you could participate in the discussion further the article could benefit from the neutral perspective of uninvolved editors. Respectfully, RomaC (talk) 13:54, 21 March 2010 (UTC)

I am happy to help if I can. Martin Hogbin (talk) 21:36, 21 March 2010 (UTC)

Faster than light

Sorry, I don't know if you'll see this. But I've been blocked from articles, discussion pages, and even, it seems, most talk pages. And as I pointed out that the blocking was unjustified, I don't expect that will change any time soon. So I don't know if you'll even see this. 216.239.82.80 (talk) 10:48, 5 April 2010 (UTC)

I can see your message OK. How long have you been blocked for? Martin Hogbin (talk) 10:52, 5 April 2010 (UTC)

A higher up person in Wikipedia persisted the blocking. Now I'll probably be in trouble for being on another IP. 216.239.88.76 (talk) 07:04, 6 April 2010 (UTC) also known as 216.239.82.80

My suggestion would be that you register then explain that you are currently blocked for edit warring and ask to be unblocked. Registering gives you a fixed identity on WP. Once you are unblocked you need to take care to remain within the rules of WP by not holding discussions on the article page and not edit warring. Martin Hogbin (talk) 09:04, 6 April 2010 (UTC)

April 2010

You currently appear to be engaged in an edit war according to the reverts you have made on Doctor Who. Note that the three-revert rule prohibits making more than three reversions on a single page within a 24-hour period. Additionally, users who perform several reversions in content disputes may be blocked for edit warring even if they do not technically violate the three-revert rule. When in dispute with another editor you should first try to discuss controversial changes to work towards wording and content that gains a consensus among editors. Should that prove unsuccessful, you are encouraged to seek dispute resolution, and in some cases it may be appropriate to request page protection. Please stop the disruption, otherwise you may be blocked from editing. magnius (talk) 14:36, 5 April 2010 (UTC)

Thanks for your comments. I note that you do not appear to be a recent contributor to the article or an administrator so I am not sure on what basis you are contacting me.

Your comments on the matter in question would be of interest as there seems to be a number of non-British editors having a bizarre argument with some native British English speaking editors as to the normal word used in British English to refer to a set of episodes. I note that you use the term 'series' on your user page. Martin Hogbin (talk) 16:02, 5 April 2010 (UTC)

Discussions are not limited to participants who speak a particular variant of the language. The discussion is a bit bizarre but you started said discussion, which is about the use of "season" or "series" relating to the classic episodes of Doctor Who and not what is the normal word for all British television programmes. Please take care to not misrepresent your fellow editors when restating their comments. Many scores of people have Doctor Who on their watchlist. The above warning likely comes from seeing the article in their watchlist. That is how i came across the discussion. delirious & lost ☯ ^~hugs~ 21:02, 7 April 2010 (UTC)

Tesla vs. Marconi deletion

I dispute your assertion (again) that the Tesla vs. Marconi section within Invention of radio is irrelevant to the article. Please do not remove it again without obtaining consensus on the article's Talk page. HarryZilber (talk) 00:28, 6 April 2010 (UTC)

Perhaps you would like to discuss the issue on the article talk page then. I have been trying to do this for some time, with no response from anyone. Martin Hogbin (talk) 09:10, 6 April 2010 (UTC)

WP:NPOV

Hi martin. Given the disagreements we had concerning evolution as fact or theory, I thought you might wish to weigh in at this discussion at the NPOV page. Best, Slrubenstein | Talk 09:05, 11 May 2010 (UTC)

Thanks for thinking of me. I will take a look. Martin Hogbin (talk) 09:24, 11 May 2010 (UTC)

IPA

Thanks for chiming in. I agree with everything you say. For months I tried to argue the same things you are saying, but I got bullied off the discussion with abuse, personal attacks, and downright insulting behaviour, but I refused to be drawn into incivility by the two defendants of everything that's wrong with their private version of the use of the IPA and its implementation in the Wikipedia.--Kudpung (talk) 15:13, 16 May 2010 (UTC)

Thanks for your comment. I am new to this subject, I was drawn in by the Worcester RfC but soon realised that the issue was much broader than Worcester.

As I see it, a relatively small bunch of editors have attempted to deal with the issue of multiple English pronunciations and have come up with a half-baked scheme that abuses the IPA and is ill-suited to the needs of WP. Worse still they are attempting to enforce their scheme throughout the encyclopedia. Martin Hogbin (talk) 15:52, 16 May 2010 (UTC)

Your perception is 100% accurate. It is sad that (bunch = 2) they are totally intransigent and remain so by blinding normal readers with pompous linguistic jargon (God knows, I' a linguist...), smoke screens, strawman arguments, deliberate off-tracking, and even exceptionally insulting behaviour. Ironically also, neither of them appear to be even qualified linguists, or to have a first hand knowledge of British English! I have prepared a proper RfC with a neutral proposition, with the help of some friends, to discuss this IPA issue. If you wish to see the draft and make any suggestions, you would have to let me know how I can contact you off line, because while it was in my sandbox it just caused more abuse and ill sentiment.--Kudpung (talk) 00:42, 17 May 2010 (UTC)

Anyone is free to email me at wiki@hogbin.org Martin Hogbin (talk) 12:24, 17 May 2010 (UTC)

Survey

Hi Martin,

I am a PhD student at the Open University of Catalonia. I am currently preparing a research project about the governance processes in online collaborative communities, and I would like to kindly ask for your collaboration based on your experience in Wikipedia. Interested in participating? Please drop me a note in my talk page. This would take around 20 of your time.

Thanks! Aresj (talk) 09:35, 24 May 2010 (UTC)

Thanks for your note. Looking forward to getting your answers. Aresj (talk) 10:32, 28 May 2010 (UTC)

Conditional solution references in lead and/or explanation

Do you object to including sentences like, "The Monty Hall problem can also be solved by a conditional probability problem, see #below." being placed in the lead or the initial explanation sections? Andrevan@ 17:44, 28 May 2010 (UTC)

I thought we had all agreed that the lead is fine as it is. What is the sentence supposed to mean? Martin Hogbin (talk) 18:02, 28 May 2010 (UTC)

The lead wasn't the key point I was asking about, so feel free to disregard it. Andrevan@ 22:57, 28 May 2010 (UTC)

Is there a typo? I do not understand what it means. Martin Hogbin (talk) 23:31, 28 May 2010 (UTC)

I asked if you objected specifically to including references to an explanation of the conditional probability analysis of the Monty Hall problem and related sub- or parallel problems in the sections which are actually primarily dealing with the simple approach. Andrevan@ 00:28, 29 May 2010 (UTC) 00:27, 29 May 2010 (UTC)

I object strongly to anything that might make the reader believe that the simple solution might give the wrong answer or answer the wrong question or that even sows the seeds of doubt in their minds about these things. "The Monty Hall problem can also be solved as a conditional probability problem" [presumed typo corrected] could suggest that there are two answers to the problem, one obtained by the simple solution and the other by means of conditional probability. Thus the reader may feel that to get the 'real' answer they have to study the conditional solution.

I also see no purpose in a statement that tells the reader that there are two ways of solving the problem when this will be self-evident from the fact that, immediately after, we show two ways of solving the problem. Any talk of 'other ways' or conditional probability etc should come at the start of the conditional solution section. Martin Hogbin (talk) 10:10, 29 May 2010 (UTC)

Clafication

Hi Martin, I just wanted to let you know that my edit summary ("Removed bad advice" ) for this removal of the two sections at Talk:Theory of relativity was not referring to the advice you gave at the bottom, but to this anonymous remark. The idea was to avoid talk page degeneration into another sci.physics.relativity madness ;-) - Cheers - DVdm (talk) 07:28, 31 May 2010 (UTC)

Thanks for letting me know. I thing the OP was a genuine young enquirer and probably did look at the pages that I referred him to, but I understand your point. The talk pages are not really the place for teaching and learning about the subject. Martin Hogbin (talk) 09:50, 31 May 2010 (UTC)

Ok. By the way, your further assistance might be needed here or on the relevant page and talk page. Thanks - DVdm (talk) 10:10, 31 May 2010 (UTC)

Happy to help. I have already commented as you have probably seen but I will try talking to the guy. Martin Hogbin (talk) 10:33, 31 May 2010 (UTC)

Notification

As you have commented in an ANI thread or RfC relating to User:Pedant17, this is to notify you that the same user's conduct is being discussed here, along with sanction proposals. Ncmvocalist (talk) 13:24, 11 June 2010 (UTC)

Possibly time to go to the Conflict of Interest noticeboard

I have left some advice on Blackash's userpage and told her that I am considering reporting her to the Coi noticeboard. She was reported once before but the discussion seems to have simply fizzled out. I plan on waiting about 48 hours to see if it sinks in before acting on this. I imagine you agree? If not please let me know what you think the best option is. Thanks, Colincbn (talk) 14:24, 23 June 2010 (UTC)

As I said on the talk page, I propose to move the page to a neutral title. If, after I have done that, if Blackash's reverts I think that would show a clear conflict of interest which should be reported to the COI noticeboard. If the new title holds then we can start discussing a new title more sensibly. I still would not rule out reporting a COI but I think it would be best to move the page first. What do you think? Martin Hogbin (talk) 15:49, 23 June 2010 (UTC)

It looks like either COI noticeboard or user RfC are the only options left now. Martin Hogbin (talk) 20:29, 23 June 2010 (UTC)

Arborsculpture

If there is any “wiki-legal” way to re-open the proposal to change the title of the article about arborsculpture to “Arborsculpture” that is exactly what we should so. THIS is the verifiable, written evidence I would have introduced had the debate not closed so quickly. --Griseum (talk) 17:22, 23 June 2010 (UTC)

As I said on the talk page, I am planning to move the page to a neutral title. We can then start the discussion about where it should finally be. Martin Hogbin (talk) 18:13, 23 June 2010 (UTC)

It looks like either COI noticeboard or user RfC are the only options left now. Martin Hogbin (talk) 20:31, 23 June 2010 (UTC)

If we can't change the title to match the article another option might be to change the article to match the title. In other-words rewrite the article to be about actual "tree shaping" and not Pooktre. Then the impetus would be on other editors to show the term "tree shaping" is not used to mean that which it is used to mean. Colincbn (talk) 03:40, 24 June 2010 (UTC)

Probably not a good idea. It would be seen by many as disruptive. Like you, I have no real interest in arborsculpture but I see what is happening on that page as an attack on the integrity of WP. It seems that one editor is able to manipulate the whole system for commercial advantage. I think COI noticeboard and user RfCs are the only way to go. Martin Hogbin (talk) 07:45, 24 June 2010 (UTC)

Except for User:Blackash, everyone who has opined on the matter of the arborsculpture article, even those disagreeing with us, seems to have the improvement of Wikipedia as a motive. Please keep that in mind as we proceed. While I empathize with your level of frustration, statements like “...I suggest that you do not give up your day job” aren't going to help our cause. Thanks. --Griseum (talk) 09:57, 26 June 2010 (UTC)

It is hard to know what to say when dealing with frivolous non-sequiturs but I take your point. Martin Hogbin (talk) 10:21, 26 June 2010 (UTC)

She is now trying to rid the entire article of the word Arborsculpture. I have never brought another user to the noticeboards, but I think someone must. I do not know the procedure but if someone can point me to the right way of doing it I suppose I would be willing. Colincbn (talk) 02:00, 20 July 2010 (UTC)

I can only suggest a user conduct RfC. I do not know exactly how you do this but I know it need two complaints. I am happy to support you in opening one. The alternative is just to revert all removals of the 'Arborsculpture'. Martin Hogbin (talk) 08:03, 20 July 2010 (UTC)

Ministerpräsident

Voting has started here. Kingjeff (talk) 03:22, 6 July 2010 (UTC)

Second round of voting has started. Kingjeff (talk) 14:02, 14 July 2010 (UTC)

Hi, friend

I'm reopening an old can of worms. Your input is welcomed... Talk:IBM_and_the_Holocaust Carrite (talk) 15:52, 8 July 2010 (UTC)

Draft on fermentation for article kimchi

Hi. This is the draft I wrote on fermentation process for the article kimchi which you suggested me to write. Please have a look and tell me what you think. I sent the same draft to User:Knorrepoes too, and asked him to proofread and revise it. Thanks. Hkwon (talk) 17:26, 11 July 2010 (UTC)

The vegetables are sliced, highly seasoned with ingredients such as red pepper, onion, and garlic, and fermented in brine traditionally in large earthenware jars. Dried and salted shrimp, anchovy paste, and oysters are sometimes used as additional seasonings. The fermentation process is initiated by various microorganisms originally present in the raw materials, but is gradually dominated by lactic acid bacteria. Numerous physicochemical and biological factors influence the fermentation, growth, and sequential appearance of principal microorganisms involved in the fermentation. The early and intermediate phases of fermentation are considered crucial to the taste of kimchi. When optimally ripened, acidity increases with sourness and a unique flavor with refreshing and coolness results from ethanol and other products.

During fermentation, which takes approximately one month depending on weather conditions, the kimchi jars are stored totally or partially underground in cellars or sheds built expressly for this purpose. Recently, however, kimchi refrigerators have become very popular in South Korea. This household electronic device maintains the temperature for the proper fermentation of kimchi, saving the trouble of burying kimchi jars underground.

It looks OK to me but I know nothing about the subject. I was also hoping that thes section might say when kimchi is fermented and under what circumstances it is eaten unfermented. Martin Hogbin (talk) 17:39, 11 July 2010 (UTC)

Spelling of Spitsbergen RFC

I've refactored my comment, and replied to your question at the RFC. Let me know if there are any further issues. Mjroots (talk) 11:36, 15 July 2010 (UTC)

Sorry it was my mistake, I misread the heading - see reply on talk page. Martin Hogbin (talk) 11:47, 15 July 2010 (UTC)

FYI

Please check out [13].Melonbarmonster2 (talk) 18:23, 21 July 2010 (UTC)

Thanks, I will add my thoughts. Martin Hogbin (talk) 18:50, 21 July 2010 (UTC)

Notice of ANI Discussion (Fut.Perf's topic ban of Hkwon)

Hello. This message is being sent to inform you that there currently is a discussion at Wikipedia:Administrators' noticeboard/Incidents regarding an issue with which you may have been involved. Thank you.Qwyrxian (talk) 12:41, 24 July 2010 (UTC)

Confidential mediation

Belatedly replied[14] to you at Wikipedia talk:Mediation Committee/Policy. I've been on holiday, and so unable to respond until now. Hope you're well, AGK 16:13, 27 July 2010 (UTC)

Thanks for that, I have replied on the mediation page. Martin Hogbin (talk) 16:33, 27 July 2010 (UTC)

interjections in talk

Martin - You've lately been breaking up comments without making it clear who's saying what. I've fixed a couple of these but can you please be more careful about this? In general, there's usually no reason you need to interject. Adding your comments at the end is almost always just fine. Thanks. -- Rick Block (talk) 14:39, 29 July 2010 (UTC)

Sorry, it makes it easier to address individual points, I will try to be more careful. Martin Hogbin (talk) 16:44, 29 July 2010 (UTC)

PQ 18 OOB

Hah! beat me to it! I was drafting a proposal for just that. Xyl 54 (talk) 23:44, 29 July 2010 (UTC)

BTW the entry for Oligarch in "Merchant ships" was the same; did you have a reason for not doing that too? Xyl 54 (talk) 23:46, 29 July 2010 (UTC)

No, I just missed it. Pleas feel free to change it, we seem to have a consensus. Martin Hogbin (talk) 08:40, 30 July 2010 (UTC)

Proposed deletion of Redefinition of the Metre in 1983

The article Redefinition of the Metre in 1983 has been proposed for deletion because of the following concern:

No reason for this to be a separate article. This appears to be mainly about the speed of light rather than the Metre. The main article on Metre already mentions this redefinition as is the appropriate place for this.

While all contributions to Wikipedia are appreciated, content or articles may be deleted for any of several reasons.

You may prevent the proposed deletion by removing the {{dated prod}} notice, but please explain why in your edit summary or on the article's talk page.

Please consider improving the article to address the issues raised. Removing {{dated prod}} will stop the proposed deletion process, but other deletion processes exist. The speedy deletion process can result in deletion without discussion, and articles for deletion allows discussion to reach consensus for deletion. noq (talk) 12:29, 30 July 2010 (UTC)

Articles for deletion nomination of Redefinition of the Metre in 1983

I have nominated Redefinition of the Metre in 1983, an article that you created, for deletion. I do not think that this article satisfies Wikipedia's criteria for inclusion, and have explained why at Wikipedia:Articles for deletion/Redefinition of the Metre in 1983. Your opinions on the matter are welcome at that same discussion page; also, you are welcome to edit the article to address these concerns. Thank you for your time.

Please contact me if you're unsure why you received this message. JohnBlackburne^words_deeds 13:47, 30 July 2010 (UTC)

MHP analysis

Okay Martin how general do you want the problem to be?Nijdam (talk) 19:01, 2 August 2010 (UTC)

Standard game rules, Monty always offers the swap and always opens an unchosen goat-hiding door. Initial car placement, player initial door choice, and host goat door choice not specified. Was there something in particular that you were thinking of? Martin Hogbin (talk) 19:17, 2 August 2010 (UTC)

Spitsbergen, (again!)

Hello Martin
Ive moved your comment down, as it was confusing where it was ( I trust you take no offense) and Ive replied (it's here).Xyl 54 (talk) 22:50, 4 August 2010 (UTC)

No problem. I was just trying to make my position clear, which is that the place is now properly called 'Spitsbergen' in English. I agree any historic names of other things ,such as the 'Spitzbergen group' of ships should be spelled as thay were a the time. Please let me know if this is not clear and I will clarify. Martin Hogbin (talk) 08:14, 5 August 2010 (UTC)

reformat

Hi. I reformatted because at first I didn't see your comment that was within my message unsigned and it might be confusing to others by being placed that way, as far as who said what. Regards, --Bob K31416 (talk) 14:01, 6 August 2010 (UTC)

No problem. Martin Hogbin (talk) 15:43, 6 August 2010 (UTC)

Merge decision for Redefinition of meter in 1983 at DRV

Thanks for drawing my attention to this. I have responded at the deletion review - basically, I made a mistake in judging the consensus in this case, and would support the decision being overturned to no consensus. Regards, -- PhantomSteve/talk|contribs\ 11:56, 8 August 2010 (UTC)

Thanks for your response. What happens now? Martin Hogbin (talk) 12:02, 8 August 2010 (UTC)

To be honest, I'm not sure. From the DRV, I would have thought that it will be overturned - but how that's done (and when) I'm not sure - it'll be an education for me too! I assume that the admin who closes the DRV will do the deed. -- PhantomSteve/talk|contribs\ 13:36, 8 August 2010 (UTC)

Thanks for letting me know, it's too bad I didn't see the message in time to participate. I would have suggested "overturn to keep" based on 1) existence of multiple reliable sources, 2) WP is not paper, and 3) the fact that it was an especially important redefinition of the unit. Also, this is fundamentally an editing question (structurally speaking, how can we most effectively present the information about the history of the meter) rather than a notability one, so it is not proper for AfD's, but should rather be discussed on the talk pages.

It's an example of a growing awkward side effect of the AfD culture - that related topics tend to get crammed into big unreadable monster articles, lest each part individually get deleted. In the big picture, this is detrimental to one of wikipedias core structural advantages over paper - namely the "mass of concise readable articles nicely interlinked" paradigm. It also makes it difficult to maintain interlinks to specific sub-topics. For example, if a reader is on a page about scientific redefinitions and clicks a link to the 1983 redefinition of the meter, she will get redirected to the article on the meter, when she is only looking for information about the particular redefinition. This happens to me all the time when I'm simply reading wikipedia and it's very annoying. AfD hero (talk) 05:49, 22 August 2010 (UTC)

Thanks for your interest. The issue has been resolved now, the article was reprieved and it has now ben expanded to incluse the whole history of the metre. Martin Hogbin (talk) 11:19, 22 August 2010 (UTC)

Mediation resumes

The mediation of the MHP case has re-started. If you wish to participate, would you be willing to check in on the case talk page here? Note that the mediators have asked that participants agree to certain groundrules. Sunray (talk) 06:58, 11 August 2010 (UTC)

Hi Martin. I have spent all day "doing my stuff" on the mediation page. In an effort to decrease my verbosity I put up some footnotes to my new mediation page contributions on my talk page. Still struggling with how to do links in wikipedia and how to get notifications when important things are changed. I hope you have time to take a look and do please comment, in whichever way you like. Gill110951 (talk)

SoL and the asymmetry of the krypton line

I thought I'd reply here to your question about how the asymmetry of the krypton line increases the measurement uncertainty of the SoL measurement, as I don't think it's controversial and the section on the talk page is getting very long ;)

What happens with an asymmetric line in interferometry is that the interference fringes get "smudged out" – that is, they are broader than would be expected for a simple Lorentzian line shape and so the fall-off in intensity between fringes is more gradual. As you're not actually "counting" fringes, but measuring intensity over a (relative) length scale, so as to be able to get "thousandths of fringes" for example, the lower variation in intensity over length means that you can be so sure as to how far along the fringe you are (for any given precision of intensity measurement, to which there are of course limits). So yes, this appears in your random measurement uncertainties as well.

I hope this clarifies things for you, feel free to drop me a line if you want to discuss it further. Physchim62 (talk) 15:08, 11 August 2010 (UTC)

Time out?

Hello Martin, do you take a break or something alike, or can we continue the analysis of MHP?Nijdam (talk) 10:21, 14 August 2010 (UTC)

I am still here. I must have missed your most recent posts. Please could your read and respond to my comment on the analysis talk page. Martin Hogbin (talk) 11:22, 14 August 2010 (UTC)

Martin, please continue the discussion on the combined doors solution. Nijdam (talk) 11:45, 22 August 2010 (UTC)

The question is what is the question

Hi Martin this is part of my personal self-discipline programme of moving off topic remarks in wikipedia mediation to off topic places, especially when I feel a burning need to respond to other peoples' remarks, whether to signify approval or disapproval (adding a constructive further twist, of course).

You wrote in the section where we are supposed to be trying to resolve the issue of what are the mediation issues

I think that interpretation, particularly of Whitaker's question, is an important issue. I do not claim that one particular interpretation is the correct one, my point is exactly the opposite. The statement is clearly open to different interpretations, some of which may represent different problems and require different solutions. Some of the possible interpretations are relevant to Rick's questions above. Martin Hogbin (talk) 17:08, 15 August 2010 (UTC)"

My response to you, and of course to anyone else interested:

Exactly; unfortunately some folks seem to find it axiomatic that all *important* MHP *formalizations* are the same. But I for one know for sure it is not true. (Of course, depends what you mean by *important*, *same*, and so on). As always in maths or logic, with strictly weaker assumptions, by definition you can't get such strong conclusions; and by definition, with strictly different assumptions, you get strictly different conclusions. There is a lot of room for strictly non-equivalent answers to poor Marilyn. She must pay her money and make her choice (choice of assumptions). I know three good strictly different minimal assumption sets which allow three strictly different valid derivations of the answer "switch", all of them supported by highly wikipedia-reliable sources, all of them supported by different people here, but mostly without realising that they could give a shorter argument with less assumptions to get to exactly the conclusion which they seem to know for sure is the only true answer to the MHP. And I learnt all this by messing with this page on Wikipedia, and I love you all for what I learnt from you Gill110951 (talk) 08:21, 16 August 2010 (UTC)

Moreover, one can multiply this multiplicity by 2 if we take account of two extreme different but both legitimate and convential interpretations of probability. Though some of the resulting possibilities are less sensible than others. I think BTW that this hidden dimension is another hidden cause of the confusion Gill110951 (talk) 08:25, 16 August 2010 (UTC)

Absolutely. I have raised this issue several times but to no avail. Rick (you are welcome to join in this conversation if you are following), in particular, seems not to be sure on what basis he is answering the question. I am not an expert on the subject but even from my understanding issue is quite complicated.

I am sure you know all this but if you can think of any ways I could explain the issues to the others it would be helpful. Possibilities that I am aware of are:

Bayesian

This is, to most people, the most natural meaning of the word 'probability', it is a state of knowledge. I would consider the principle of indifference to be inherent to the Bayesian concept of probability, but even so I have no objection to the requirement that it is explicitly invoked if required.

From the player's SoK, and applying the PoI consistently, the answer is plainly 2/3, as the player would have no knowledge of the host's door policy. If we choose not to apply the PoI the problem is insoluble. It is only by applying the PoI inconsistently that Morgan's result can be obtained. These results apply to the unconditional case and when given the condition that the player has chosen door 1 and the host opened door 3.

Comments: Other names for Bayesian: subjective, personal, epistemological. Probability is a property of our beliefs.

There is a wonderful theorem that a person who makes bets self-consistently behaves as if they are using probabilities (this is also the basis of a lot of mathematical economics and finance). I have nothing against it whatsover. But I emphasize: garbage in garbage out. If you put subjective probabilities in you get subjective probabilies out. The PoI means that the guy who knows nothing would obviously bet with equal odds on any of the three doors, he would obviously be bet with equal odds on the quizmaster opening either door when he has a choice, so to be consistent he would bet at odds 2:1 after choosing door 1 and quizmaster opening door 3, that the car will be behind door 2. Gill110951 (talk) 13:29, 17 August 2010 (UTC)

Frequentist

Despite advice in the Morgan paper not to do so, Rick likes to try to apply a freqentist approach to this problem. He claims that if 'the experiment' is repeated many times, the results will depend on the host's door opening policy. The problem, as Morgan rightly point out, is that the outcome depends on exactly what experiment you repeat.

If the producer always replaces the car behind door 1, and the host always chooses door 2, the player always looses by swapping.

If we have a producer with some fixed policy on initial car placement and a host with some fixed policy on goat-door opening the answer will depend on the two policies, and if these are unknown, the problem will be insoluble.

If we have a producer who always places the car uniformly at random and a host who chooses a goat-door uniformly at random the answer is 2/3.

Again, these results apply to the unconditional case and when given the condition that the player has chosen door 1 and the host opened door 3. The results are also, as might be expected, consistent with those from a Bayesian approach. Morgan's result only applies if the producer's car placement and the host's door choice are treated differently.

Comments. Other names: objective, ontological. Probabilities reside in the things themselves of in the configuration of things, in the situation. I also like to think of many many repetitions. Imagining many repetitions allows one to guess what the probabilities would be in many physical situations and in many situations with symmetries. If there are probabilities at all, then the long run relative frequencies are the same as the probabilities. Imagining many repetitions is an intellectual discipline which forces you to fix in your mind what we are talking about. What is to stay the same, what is allowed to vary in some natural arbitrary way.

But also for subjectivists, their subective probabilities can be "guessed" by thinking of imaginary repetitions. Your subjective probabilities reflect what you think would happen in many many repetitions in a kind of imaginary parallel (counterfactual) worlds where everything you know about for sure is the same, but anything else might be different. So a different horse can win the race every time. Why else would you bet at certain odds on a certain horse? The difference between frequentist and subjectivist is therefore merely what is repeated; is it repeated (in the mind) in parallel, or in sequence? Frequentist probability is equally "subjective" somewhere since you never are going to see an infinitie number of repetitions and if you did you wouldn't be using probability. Both kinds of probability require some kind of reference frame, and the choice of frame is up to the user of probability.Gill110951 (talk) 13:36, 17 August 2010 (UTC)

Modern probability theory

Rick once raised this subject in order to show that the 'real' probability is 1/(1+q) but the 'average' probability is 2/3!

When I read up on the subject it is clear that mathematicians have developed a theory for manipulating probabilities. Because of the philosophical problems surrounding the meaning of probability they have decided to leave that question out of the subject. Probability values are assumed for every event in the sample space but, as the WP article states, 'The modern definition does not try to answer how probability mass functions are obtained; instead it builds a theory that assumes their existence'.

The mathematicians have basically said, sort all the philosophical stuff out first and come up with the probabilities of all the events in the sample space then we will show you how to manipulate these probabilities to get the answer you want. Using this formalism we get the same result as before. With unknown distributions of player choice, initial car placement, and host goat-door choice the problem is insoluble. If these are all uniform at random the answer is again 2/3.

Comments. The same calculus applies to subjective and to relative probabilities. "Modern probability theory" is completely neutral as to the field of application. I don't think the choice of objective/subjective is a philosophical choice, it is a practical choice determined by the application. The mathematicians recognise this and simply tell you what will be true about all probabilities, whatever their flavour.

But I think the stuff about 1/(1+q) being on average 2/3 is about something else. Moreover it is not true that the thing is insoluble with unknown distributions and so on and so on. Maybe the conditional probability is not uniquely determined if you haven't uniquely fixed everything, but why should you, when the answer is the probability is always at least 1/2 and on average it is indeed equal to 2/3? Incidentally that is merely the law of total probability. You and others use it all the time! P(A) = P(A|B1) x P(B1) + P(A|B2) x P(B2) + ... when B1 B2 ... are alternatives which do not overlap but together do exhaust all the ways that A can happen. The unconditional probability is the average over the conditions, of the conditional probabilities Gill110951 (talk) 13:48, 17 August 2010 (UTC)

When I say it is insoluble I am talking about a specific case, which is that no assumtions are made about any of the unknown distributions and that the player has chosen door 1 and the host has opened door 3. In this case, if we choose not to make any assuptions about the distributions or apply any principle such as the principle of indifference then the answer can clearly be anything from 0 to 1. The producer might always place the car behind door 1, for example.

Regarding your comment, 'The same calculus applies to subjective and to relative probabilities' that was exactly my point. Modern probability theory specifically avoids fixing the probability model. Martin Hogbin (talk) 08:50, 20 August 2010 (UTC) Martin Hogbin (talk) 08:50, 20 August 2010 (UTC)

Exactly. NB: relative frequencies in, relative frequencies out. Rational betting odds in, rational betting odds out.

In science we take fate into our own hands. In experimental science we use carefully designed randomly selected experimental designs. In observational science we take a carefully designed random sample. When we apply decision theory and game theory to the real world we will find ourselves using deliberate and carefully designed random strategies. The best optimization algorithms are randomized with carefully tuned randomness all the way through. Smart people on the Monty Hall show thought about the problem in advance and picked a door number by randomization. They get a hard and objective guarantee of unconditional 2/3 according to whatever probability model you like, and it's the best you can get; their strategy is random choice and then switch. Conditional probabilities are simply totally irrelevant.Gill110951 (talk) 04:54, 21 August 2010 (UTC)

Player's initial door choice

As my analysis page shows and we have both pointed out several times, if the player chooses a door initially uniformly at random, the answer is 2/3, regardless of the initial car placement or the host policy.

If we are told to apply the condition that the player has chosen door 1 and the host has opened door 3 than all the above applies. The answer is still 2/3 (or indeterminate) unless we are inconsistent in out choice of unknown distribution. Martin Hogbin (talk) 11:44, 16 August 2010 (UTC)

IF the player chooses a door uniformly at random the UNconditional probability switching will give him the car is 2/3 regardless of the intial car placement of the host policy. Yes. That is the game theoretic approach in its informal version. You can kind of make this COMPLETE from the point of view of game theory by noticing that it's inconceivable that one could get a better UNconditional probability than 2/3, WHATever way the car is hidden and a goat door opened. On the other hand, ANY other stategy than "randomize uniformly and later switch" is such that if the quizmaster could have anticipated you would have used it, he could have hidden the car and opened a door in such a way that your UNconditional probability of getting the car fell strictly below 2/3.

Not only is randomize/switch an eminently sensible strategy, it cannot be beaten without knowing something about what the quizmaster is going to do. At the same time if he hides the can uniformly and opens the goat door uniformly (when able) you cannot do better than 2/3 anyway. This is called the minimax solution. In practice, sensible players and sensible quiz teams will use their respective minimax solutions.

Note that if you initially choose your door uniformly at random then the answer is unconditionally 2/3 independent of what you mean by probability, independently of any warrented or unwarranted assumptions about the quizmasters. The point is there are actually TWO moments when the player takes an action and actually, the first is just as important as the second, but many people don't realize this. The statistics 101 literature is pedagogical, its about the difference between conditional and unconditional. It's not about "Suppose you WILL be on a game show tonight. At this game show, what always happens is this..." Gill110951 (talk) 13:57, 17 August 2010 (UTC)

Now you're getting into the producer's State of Knowledge of how the contestant will select a door. I think this is as contrived as the contestant knowing of a host bias. Even if the contestant's 'lucky number' is 1, the producer is unlikely to (now way to?) know this. It's a game show, anyways. The producer may be required to (or simply choose to) use a randomizing technique for the car placement. Glkanter (talk) 14:09, 17 August 2010 (UTC)

Besides, you're suggesting that 'The contestant will choose uniformly at random, or per a proscribed methodology'. I don't buy it. People do not always act rationally (and who's to say what is 'rational' when choosing doors?). Maybe the contestant will hear a loud voice from the audience yelling a door number and choose that door. That's neither uniformly at random or a predictable choice. The contestant himself is likely to answer 'I dunno', or 'It just seemed like a good door', rather than give either of the explanations you suggest, if asked 'why that door?'. Glkanter (talk) 14:20, 17 August 2010 (UTC)

NO, and NO, Garry. Please take a step back. First of all I think of the player before they go on the show. They'll not be able to think straight while on the stage under all those lights and if they are smart they'll have thought about all this ahead. Of course on the stage no-one switches. Suppose you're on a game show.. what do you do? Not switch of course! (Unless you're a pigeon). But suppose you're going to be on a game show.. what will you do!!! Much more relevant and interesting and enlightening question. Secondly I am not saying that all players will use game theory to do the right thing (randomize and switch). But some might. The quiz show folks are smart. They also want to protect themselfs from the management school and finance PhD's who come on the showGill110951 (talk) 14:31, 17 August 2010 (UTC)

"Suppose you're on a game show..." On Let's Make A Deal, the player did not know he would be selected until the announcer (or maybe Monty) called his name. That's why everybody wore wild outfits, to attract attention to themselves. Also, they did not know which games Monty would play that day. The producer knowing of a contestant bias is a contrivance. No better than than Morgan's host bias that the contestant supposedly might be aware of. Without it being a premise of the puzzle. Which is why, when I used to argue 'who is right', I would argue that doors 1 and 3 were not premises of the MHP per any reliable source, and therefore it was illogical to say the solution must be conditioned on them. But, I'm no expert on these things. Although you and Nijdam seem to agree that every reliable source has it wrong. So, who needs experts? Glkanter (talk) 14:51, 17 August 2010 (UTC)

One final piece of pedantry

I think Nijdam and Glopk accept all the above but still argue that we must deal with the (agreed fully symmetrical) problem using a formalism of their choosing and in a way that shows both the host's goat door options (but curiously not all the player's initial door choices because symmetry makes thus unnecessary). Maths is full of short cuts, often based on symmetry. If you can show that it must give the right answer, it is correct.

Nijdam has accepted that even he would take the same short cut that is used in the simple solution in an urm problem that I put to him:

An urn contains 10 balls numbered 1 to 10. You remove two balls, neither of which proves to be number 10. What is the probability that the next ball will be the 10? Easy way, there are eight balls left, one of which is the 10... Hard way, the full sample space contains 10 * 9 * 8 elements, we must calculate the probability of each event... I can even prove you need to do it the hard way by considering the variant where the balls are of different sizes and thus may have different probabilities of being picked. Martin Hogbin (talk) 12:02, 16 August 2010 (UTC)

Symmetry and stuff. Good mathematicians, smart physicists, are always noticing ways of arguing what the answer must be without calculating it from first principles. That latter is for beginners. One has to learn the hard way. First you learn the rules, then you internalize them and then you learn to operate on a higher level. Like playing chess. The process never stops, there is always a higher level. Gill110951 (talk) 14:03, 17 August 2010 (UTC)

Two mutually obfuscating problems

The conditional solution deals with two problems each of which obfuscates the other.

The most important problem is the basic (unconditional if you like) MHP. This is what fools nearly everyone and what needs to be carefully explained in the article. It is plenty hard enough without the obfuscating issue of which door the host chooses.

The basic MHP hides a fundamental philosophical problem which, on its own, can be stated very simply. A person chooses one of two doors, numbered 2 and 3. What is the probability that they choose door 3? Martin Hogbin (talk) 17:39, 16 August 2010 (UTC)

I agree that the unconditional problem is basic, important, needs to be carefully explained.

Your second problem is indeed fundamental but it is finessed in two ways, (a) with mathematicics and (b) by seeing the game theorists' point of view. Moreover, (c), it is indeed philosophical, but according to one legimitate world-view in epistemology (Bayes, Laplace) it has an easy answer (1/2, by the Principle of Indifference). According to the other world-view (von Mises, Popper?) it is unanswerable, but this is no problem with (a) and (b). For the mathematician an easy analysis shows that the unanswerability of the question is irrelevant, see (a) below. For the Game Theorist the unanswerability is irrelevant since he looks at the problem from a slightly higher point of view and makes the unanswerability irrelevant by taking fate into his own hands by tossing a dice. Cf.: why we use randomization to fix experimental designs in experimental science; why we take random samples to get unbiased and objective information in observational science.

I think right now that this is the short way to understand all meaningful controversy on the MHP. Hence understanding three ways to get around the second problem is also fundamental in resolving debate on MHP. You hit the nail on the head, man!!!!

The mathematician will notice that if all doors are initially equally likely to hide the car, then by the odds form of Bayes rule one immediately sees that the conditional probability is 1/(1+q) which is at least 1/2 and on average 2/3. The mathematician will tell you to switch doors, and he doesn't need to tackle any problems at all whether philosophical or practical about what is q.

The game theorist finesses this in another way. He doesn't care a damn for philosophy, he wants to optimize. He finesses it by putting hard objective probability under his own control into the problem himself.

For the Laplacian (= the rational subjectivist, = rational Bayesian, = rational adherent of "probability is epistemological not ontological" view) there simply is not an issue. According to his knowledge the door numbers are irrelevant hence they're irrelevant. Hence the "conditional probability" is also 2/3 but that is irrelevant since the numbers are irrelevant. Irrelevance (which is a state of knowledge) implies probabilistic independence, of course.

There are more ways for the mathematician to get this "at least 1/2" result. By the law of total probability, the conditional probabilities average out to the 2/3 of the unconditional question. If any of the conditional probabilies would be smaller than 1/2, then under that condition, you could do strictly better by not switching. But if that was the case, there would be another strategy with sometimes switching, sometimes staying, which would be strictly better than always switching, hence strictly better on average than 2/3,but no one has ever come up with a way to beat 2/3 and I for one am certain they never will. Because I know they can't. Gill110951 (talk) 14:18, 17 August 2010 (UTC)

The strong unconditionalists were right all the time

I think I know why "unconditionalists" often know that they are right and complete and there is nothing more to be said. It is Bayesian versus frequentist. Probability as epistemological versus probability as ontological. Laplace and Gauss and most everyone up to the end of the 19th century versus von Mises and most everyone from the 1920's to 1990's.

This is what I just wrote at the end of a new sub-item [15] on my talk page: "it is totally correct to believe that the short intuitive solution is not only correct but also complete. ie it is the last word on the MHP ... *if* we take a certain very wikipedia-reliably sourced metaphysical position in epistemology (the science that studies what it means to know something). Reliably sourced both at the expert and at the layperson's level". Gill110951 (talk) 07:30, 19 August 2010 (UTC)

The phenomenon of the Monty Hall problem

Hi Martin:

It strikes me that the editing on the Monty Hall problem is an unusual example of behavior on WP. I wonder if you would describe it as an impasse?

It interests me because it looks like all parties have managed to maintain their cool over a very extended period of time, and yet are no closer to agreement than they were years ago. What is more surprising to me is that it breaks a rule that I thought I had discovered about WP behavior, namely, that any discussion that persists more than a few iterations inevitably ends up in AN/I and eventually in an ArbCom hearing that locks somebody out of the discussion to enable a resolution.

Why is that? Is it because the opposing factions have balancing strengths, so a minority cannot be identified to shut up? Is it because there are allies in high places on both sides? Is it because this topic is a rare example of what should normally happen in an irresolvable case if misguided administrators keep their hands off?

What is your view? Brews ohare (talk) 18:15, 21 August 2010 (UTC)

If I may...

Mr. ohare, I've followed some of your exploits from afar. I must say, you are quite resilient! I think the answer is very simple. Both sides are certain that they are 'right' as per Wikipedia policy. No hidden or demonstrated agendas, no hidden or demonstrated advocacy of political POVs, no Wikipedia backroom clout (as far as I know), no nothing. Just 2 pretty evenly matched (however that may be defined) adversaries, whose editors, at this point, are not willing to concede. All of whom (I may be the worst, certainly top 3) who should take the time they spend on this dopey article, and do something to make the world a better place.

As for the admins, this article has a reputation for being a quagmire. It's also of little societal or political import and likely has a low external-to-Wikipedia visibility. So, I think uninvolved admins prefer to leave us be as much as possible. Glkanter (talk) 18:33, 21 August 2010 (UTC)

Thanks for your observations from the inside of this controversy. Brews ohare (talk) 23:44, 21 August 2010 (UTC)

You're welcome. It really defies rational explanation. You might appreciate the section on my talk page called 'Conventional Wisdom'. Glkanter (talk) 02:05, 22 August 2010 (UTC)

I read "Conventional wisdom". It raises the question of how minority views can be heard, a question I wrote an essay about. If you are so inclined, please comment on its discussion page.

As a very broad matter, the treatment of all such questions of WP organization presently is left to chance, or to "democratic" evolution (if you like that description), a process that never will work. What is needed is something better than hopeless yakking about policies. For example, a formally recognized procedure for trying things out for a while to see what happens. Any other suggestions? Brews ohare (talk) 05:26, 22 August 2010 (UTC)

Brews, I agree, it is rather puzzling. Some editors came to the page because of an RfC two years ago claiming issues of page ownership by a group of editors. In that time, the page has changed a bit, for the better in my opinion.

As you will, no doubt, have gathered, the main argument is about the validity and acceptability of the simple solutions. The original editors consider a specific form of solution, based on conditional probability to be the only correct and complete solution. Others, including myself and Glkanter believe that there are many reasons why the simple solutions are valid and acceptable.

The problems now are essentially over interpretation and weighting of sources and presentation. Although the maths was argued over for a while, I think this was something of a (maybe accidental) smokescreen put up by the conditionalits but now I think there really is no argument on what the correct answer for any given problem formulation. Some disagreement on whether a simple solution is complet and correct, even though it gives the correct answer.

I am reasonally hopeful that the mediators will move us on towards an agree article. Then, of course a bunch of new editors will come along... Martin Hogbin (talk) 11:14, 22 August 2010 (UTC)

You may have seen that this dispute resulted in the publication of a letter from Nijdam and myself (who seem to be on opposite sides in this dispute) in a peer-reviewed journal. I am not sure if it has ever happened before that a WP dispute has actually changed a reliable source. Martin Hogbin (talk) 11:24, 22 August 2010 (UTC)

Hi Martin: I hope that WP can achieve that result again, as that would indicate WP editors can evolve to write about questions not previously posed. That is a big advance over clubbing people you don't agree with. Brews ohare (talk) 15:00, 22 August 2010 (UTC)

Such cooperation is the real reward of being an editor on WP, as opposed to preening and running in gangs. It's pretty rare. Brews ohare (talk) 15:04, 22 August 2010 (UTC)

The process has also led to two peer-reviewed articles by myself, one in an encyclopaedia of statistics, the other in an international journal. The reason why views become so entrenched is in itself interesting. It has a lot to do with different intuitive concepts of probability. Gill110951 (talk) 13:21, 24 August 2010 (UTC)

Reverting edits

Martin Hogbin you really shouldn't have reverted Sydney bluegum's edits on Tree shaping. They made multiple changes, you should have made the changes you disagreed with and left a comment on their talk page as to why. I have revert your edit, but I did put back arborsculpture, put in a fact tag and fixed up the Grown furniture. The rest seemed fine. Blackash have a chat 13:43, 24 August 2010 (UTC)

Blackash, I think the problem lies with Bluegum. If you are going to make obviously contentious changes it is best not to mix them into a single edit with other changes. Martin Hogbin (talk) 20:16, 24 August 2010 (UTC)

Human

Please comment on the talk page (Talk:Human) before making any drastic changes. You wrote in comment line: "Restored original lead pending further discussion on what we are trying to achieve. No consensus for change at this time" - None of which is actually true: 1) your undo was a revert, not a 'restoration', 2) there is no "original" version, just a older version you happen to prefer, 3) "pending further discussion" makes it appear that you have been participating in discussion, when you haven't responded to comments even from the day before yesterday 4) "what we are trying to achieve" gives the impression that your impetus is consensus, when others yesterday agreed (tenatatively) to a merge version (If you want to contradict certain elements in the merve version please do so on talk and be specific), 5) contrary to your claim of "no consensus" there in fact is some consensus between Cybercobra and I and even Ucucha agreed that my alteration of the Cybercobra's merge was an "improvement." Regards, -Stevertigo (t | log | c) 21:34, 2 September 2010 (UTC)

For anyone wondering if the accusations against Martin Hogbin by Stevertigo may have some valid basis, the answer is no. I came to this page to thank Martin for taking a firm stand against the unwarranted changes to Human that Stevertigo has been trying to implement. It is Stevertigo who made the large changes and then failed to gain consensus for those changes. Johnuniq (talk) 23:58, 2 September 2010 (UTC)

Note: see Talk:Human for a clearer picture - one which entirely negates anything that Johnuniq has to say. -Stevertigo (t | log | c) 01:09, 3 September 2010 (UTC)

Talk page chat

Hi Martin, rergarding these edits of mine ([16], [17], [18]), please try not to engage in endless technical discussions on the article talk pages? I think the best thing to do is to just demand a reliable source for whatever it is they want to add to the article, if they have anything to add to begin with. Otherwise point them to Usenet :-) - See also this section on my talk page. Cheers, DVdm (talk) 17:19, 20 September 2010 (UTC)

What is the matter with you Dirk, do you not want to fill up the WP talk pages with the ranting of crazy people? Martin Hogbin (talk) 22:16, 20 September 2010 (UTC)

Spot on :-) - DVdm (talk) 06:36, 21 September 2010 (UTC)

Gadsby

Hi Martin, Padillah is now rationalizing obviously that a solitary word ("his") should bow down in favor of his own solitary word (T, H, you-know-what). But Wright said "his" and not Padillah's word. Is your hat in this ring? JJB 18:34 2010-09-27 (UTC)

The consensus, in my opinion was always to have a lipogram as the main text. Martin Hogbin (talk) 19:06, 27 September 2010 (UTC)

On the MHP article unlocking request

See: this comment. Q.E.D. glopk (talk) 18:19, 1 October 2010 (UTC)

User:Gill110951's name is Richard

Please use Richard's real name, he said "please call me Richard"     Regards, Gerhardvalentin (talk) 13:28, 2 October 2010 (UTC)

I can confirm this! My name is Richard Gill, most people call me Richard, and I'm very happy with that. Gill110951 (talk) 13:31, 2 October 2010 (UTC)

No problem. I know your name is Richard but I was not sure that this was public information on WP. Martin Hogbin (talk) 14:36, 2 October 2010 (UTC)

I've taken the Gadsby discussion to ANI

Hello. This message is being sent to inform you that there currently is a discussion at Wikipedia:Administrators' noticeboard/Incidents regarding an issue with which you may have been involved. The discussion is about the topic Gadsby: Champion of Youth. Thank you. Padillah (talk) 13:22, 25 October 2010 (UTC)

What do you think I should do now, Martin? JJB 05:58, 31 Oct 2010 (UTC)

Section title

[19] ... but by all means, if you feel better with your version, feel free to undo :-) Cheers - DVdm (talk) 18:46, 6 November 2010 (UTC)

No, your version is better. I do not believe that this term is in standard use within Lagrangian mechanics in general although the quoted sources show that it does have some limited use, mainly in robotics. Martin Hogbin (talk) 23:04, 6 November 2010 (UTC)

Undoing multiple revisions

Hi Martin, thanks for your undo's of the anon edits at One-way speed of light, in response to my inquiry on the talk page. I notice that you undid all the edits separately. Perhaps you don't know, but I found a quicker way to do this:

1. Go to the page history and click undo on one of the editor's edits (it doesn't matter which one),
2. In the preview window, copy the edit summary ("Undid revision 397101027 by 194.225.71.139 (talk)") to the clipboard buffer (control-C),
3. Without saving the undo edit, go back to the page history window, and make a "Compare selected revisions" between the version to which you want to go back, and some arbitrary more recent version,
4. In the diff window (see example), click the (edit) link next to the revision header on the left (Revision as of 18:10, 23 October 2010 (edit)),
5. You get a warning that you are editing an old version, which is what you want,
6. Paste (Control-V) the edit summary you had copied before, but remove the revision number and turn "revision" into "revisions", and complete the summary with an appropriate reason ("Undid revisions by 194.225.71.139 (talk) Unreliable source and wp:NOR"),
7. Show preview, verify and Save Page.

Sounds a bit complicated, but it's actually really simple and straightforward. Cheers - DVdm (talk) 09:27, 17 November 2010 (UTC)

Thanks, I have always wanted to know how to do that. It was fairly clear to me that the changes were the anon's OR. Certainly anything that contradicts Zhang on the subject would need very substantial verification. Martin Hogbin (talk) 10:16, 17 November 2010 (UTC)

MHP Consensus is not unanimity

Dear Martin,

I am wondering what it means that MHP editors can reach consensus without unanimity. I think it helps if we will avoid words like "correct", "true" and be very very careful with formulations. And try to write things which a large majority of the editors can sign up to, a different large majority each time, so that no one is left out, everyone gives and takes a little.

Let me give an example from your latest posting to explain what I mean. You wrote

2 The simple solution are in fact correct, with the application of an obvious and intuitive symmetry

This is certainly your personal POV and no doubt three of four editors share with you, but you can't hope to get anything like consensus since it is in direct opposition to a personal POV of three of four other editors.

The problem is the word "correct" and where you place it. Professional mathematicians and ordinary laypersons will disagree what "correct" means. Ordinary lay persons will stay disagreeing whether the simple solution is correct with or without the application of the obvious??? and intuitive??? symmetry which almost no-one ever mentions in print. Pedantic professionals like Nijdam and myself will say that what your wording is so misleading that we can never accept it, independent of our POV. Can't you express yourself in a way which the nitpickers can still sign up to? Nijdam's POV is that the MHP *must* be solved by finding a conditional probability (Morgan et al. are on his side, and so are Carlton and Rosenthal, I believe) and that if you don't explain why the 2/3 you have found with the simple solution is also the conditional probability, your solution is wrong (your arguments are incomplete). Couldn't you have said something like: Simple solution plus symmetry can be together packaged as a correct rigorous intuitive complete beautiful solution of the conditional problem. This is done explicitly by Gill (2010, 2011) not because it's a big deal but because no one put it in print before, as far as I know. Morgan et al only alude to it ... but not well enough for every professional to understand!

Now Glkanter can object that I can read words in Morgan et al. which he doesn't see there. Too bad. Nobody can have it all exactly their own way. Many editors will remain insisting that the conditional probability and the unconditional probability are different concepts, it doesn't matter a hoot whether you are a professional or a layman, everyone must realise that 2/3 of all the games is different from 2/3 of the games that the player chose 1 and the host opened.

By the way, about the "obvious" and "intuitive", why the hell then did not Carlton or Rosenthal write down the couple of sentences necessary to add this into their nice papers? Obviously it is not so easy to pick up, out of the Morgan et al. stuff; I find their papers very opaque. Remember, all these guys are supposedly professionals in teaching probability and statistics but seem blind to this "obvious and intuitive" and completely rigorous route to finding the conditional probability! Morgan et al. noticed it as an afterthought, nobody else picked it up.

So you wrote down your POV, some might agree some might not, but we can never get anything like consensus. How about this three-parter instead

2-1: According to reliable sources Morgan (1991b) and Gill (2011), an alternative route to determining the probability that switching gives the car given player chose 1 and host opened 3 is via the simple solution and the symmetry of the problem as expressed for instance in the K&W assumption.

2-2: The POV of reliable sources Carlton, Rosenthal, and Morgan et al is that a solution is only complete/rigorous/correct if all links in the chain of reasoning are logically correct and if the chain of reasoning ends with explicit mention of the *conditional* probability that switching gives the car given ... (a different concept, though often not a different number, from the unconditional probability).

2-3: The POV of reliable sources vos Savant, Barbeau, ... is that the simple solutions are in themselves complete/rigorous/correct.

I think you could get consensus (not the same as unanimous agreement!) about that.

Richard Gill (talk) 12:06, 26 November 2010 (UTC)

If I may intrude briefly, the article need not, and should not, address 99% of what you discuss above. Its an article about a puzzle, not a probability primer. Martin's use of 'correct', I believe was only meant to call for the elimination of the Nijdam's, and the current article's POV of '1 car, 2 goats (previously known as 'simple') is the wrong way to solve the problem'. Neither POV should be in the article. The solutions should be presented without any editorializing. With the new section titles I proposed, ('1 car, 2 goats' and 'door 1 and door 3') each reader will easily find the solution to his interpretation, and immediately understand that there is a difference, and what that difference is. (Could the high priests handle that? That the reader finds his own way, clearly, without being led by the nose to the priests special enclave of knowledge?) Elsewhere in the article is where the minority POV of perhaps G & S and Grinnell ('1 car, 2 goats is the wrong way to solve the problem) could be recognized (it is so minority, does it really require inclusion?), without judgment. Glkanter (talk) 12:27, 26 November 2010 (UTC)

What was hopefully about to be discussed is not about what should be in the article, but about an idea I had about how to let the mediation progress more smoothly. Which I put to Martin using one of his sentences as an example. I'm looking forward to his own reaction. Richard Gill (talk) 14:12, 26 November 2010 (UTC)

Richard, I think we are talking about different things. Maybe my wording was not good. I, like you, do not want to talk about solutions being 'right' or 'wrong'. There are many different types of solution with varying degrees of rigour. The most rigorously correct solutions would probably be completely incomprehensible to everyone except specialist mathematicians.

When I said 'correct' I was really meaning to say 'acceptable', 'justifiable at some level', or 'fine in the proposed context'. Of course, what I wrote was my POV just as what Rick wrote was his POV and my wording was, to some degree, a quote from Rosenthal.

What needs to be established before we will get a consensus is that the simple solutions are not 'wrong', which seems to be the fixed and immovable view of Nijdam and maybe Rick and Glopk. If we can work towards the view that the simple solutions are not 'incorrect', 'answer the wrong question', or incomplete to an unacceptable degree we have a chance of gaining consensus. Martin Hogbin (talk) 14:26, 26 November 2010 (UTC)

I apologize for hijacking your discussion, Richard. I assure you, when you have this same discussion with Rick, Nijdam, and the others, I will *not* intrude. Glkanter (talk) 14:30, 26 November 2010 (UTC)

Agreed, Martin. You presented what you called three facts. But they're not all facts, number 2 was a point of view. It's important to keep making the distinction. Report the opinions of sources. It's a fact that your number 2, interpreted charitably, is the opinion of some important sources. The wikipedia pages should continually make it clear that we are presenting the *opinions* of various sources, it is not for us to say whether or not they are also true facts.

Let's present the simple *opinions* first, that's what people most people want to read. Then present the *opinion* that the simple solutions are inadequate. Then present conditional solutions, focussing on that particular conditional solution which minimizes the distinction: simple plus symmetry. Nijdam will object to the ordering and to the postponement of so-called health warnings to one place, but the mediators will overrule his objection because he'll be alone in this extremist viewpoint. Glkanter will object that it is stupid to present the opinion that 2/3<>2/3. But so what, readers who don't understand what that section is about will skip it. Nijdam could better use his energies finding good ways to explain *why* you should do it conditionally, or citing authorities who give good reasons, rather than just dogmatically repeating that you have to condition, and citing authorities who are equally dogmatic. Richard Gill (talk) 18:35, 26 November 2010 (UTC)

I presented my opinion as fact but that is pretty much what everybody is doing at the moment. All I was trying to do was get some discussion going on the intended subject, which is the criticism of the simple solutions. If we can all start to discuss the relevant issues we might be able to reach a conclusion on them. I have made many attempts at compromise, the others need to give a bit. Martin Hogbin (talk) 20:16, 26 November 2010 (UTC)

OK, I understand. And I agree wholeheartedly with your last sentence. Richard Gill (talk) 05:48, 28 November 2010 (UTC)

Response to your comment

I responded to your comment on the mediation talk page here. I would appreciate hearing your thoughts on this. I think we have to do something dramatically different. However, participants may not be able to reach an agreement. I am looking at all options at the moment. Sunray (talk) 22:23, 2 December 2010 (UTC)

Speed of light FAC

I have nominated speed of light for FAC. As a major contributor, please leave your 2cents on the review page.TimothyRias (talk) 16:05, 6 December 2010 (UTC)

Starting points

Martin, I'm trying to find out on which points editors do agree. Please see Wikipedia talk:Requests for mediation/Monty Hall problem/Starting points. Nijdam (talk) 14:12, 13 December 2010 (UTC)

New example

To make you understand the error in the simple solution, I give you a new example.

My son will paint the wall in the living room in his new house. He still has to decide between three colours: White(W), light green(G) or light yellow(Y). He will need 10 liters paint, costing: W: 30 euro, G: 40 euro and Y: 45 euro. I have offered to pay for the paint. How much will I have to pay? The only answer will be: if he uses W then 30, etc. What if he decides at random? Would you give a different answer? You could of course calculate the expected amount I will have to pay, but would you consider that the correct answer. But after he has painted the walls, what then? Don't you agree that the answer is still: if he uses W then 30, etc? Now what if all the colours were of the same price? Would that make any difference of 30 euro? The only difference is that I'm sure I'll have to pay 30 euro. But not because this is the expected amount!! Nijdam (talk) 01:13, 1 January 2011 (UTC)

Nijdam, I a very happy to talk to you about this subject but it would help if you did not keep refusing to answer because you claim have already told me the answer. Maybe you did not explain the right thing or maybe you did and I did not understand. Just eplain again, it is much simpler.

I am not sure which point of disagreement your analogy above refers to. Could you explain please. Martin Hogbin (talk) 11:27, 1 January 2011 (UTC)

I don't know which question I seem to refuse to answer. The example above shows that the answer is always on the condition of the chosen colour; even when all the prices are the same (symmetric case). I.e in the MHP the answer should count for the situation the player is in, even in the symmetric case, hence calculate the conditional probability. I have on several occasions shown why the simple solution (reasoning) (as per Savant, Devlin etc) is wrong. Do you in the mean time understand this? Nijdam (talk) 12:30, 1 January 2011 (UTC)

Let us go back to the MHP then. Do you agree that in the symmetric case the probability that the car remains behind door 1 is unchanged when the host opens a door? Martin Hogbin (talk) 12:34, 1 January 2011 (UTC)

We've been through this before: the probability is changed of nature, from unconditional to conditional, both with the same value for the event of door 1 hiding the car. They really are different probabilities, based on different sample spaces. This is, I think, the only point you have to understand. Nijdam (talk) 13:16, 1 January 2011 (UTC)

A HAPPY NEW YEAR to all of you!   W.Nijdam: "P has changed of nature, from unconditional to conditional, both with the same value."  Does that mean that the unconditional value however wasn't correct (enough)?   Or that the unconditional value was just "nonproven", that means "the mathematical proof" had still been missing, and so it had to be checked and it was found to be correct? Or quite another meaning, like transubstantiation? Who can clearly expound that "difference in nature", graspable enough for the reader? Regards,  Gerhardvalentin (talk) 14:33, 1 January 2011 (UTC)

OK, so the numerical value of the probability that the car is behind door 1 is unchanged by the host opening a door in the symmetrical case. Agreed?

You seem to be giving some additional properties to the term 'probability'. As I understand it, probability is a number, a scalar, it has no dimensions or components it has only a numerical value. Is this not correct?

You also seem to be saying that any value of probability has associated with it a unique sample space. I do not agree, there may be more than one sample space that could be used to determine any required probability. Martin Hogbin (talk) 14:18, 1 January 2011 (UTC)

3 apples are different from 3 pears. Two probabilities can have he same value without being the same thing. Saying that the probability the car will be behind the other door is 2/3, is different from saying that the probability the car is behind Door 2 given Door 1 was chosen and Door 3 opened is 2/3. If you are a frequentist you are referring to two thirds odd different ensembles of repetitions. If you are a subjectivist you are referring to acceptable betting odds in different situations. What Nijdam has so far failed to explain to us is why you *must* solve MHP with conditional rather than unconditional probability. I am not aware of any moral or ethical content of mathematics, so I don't understand how he thinks mathematics can dictate what we should do. However, I did offer two motivations, one for the subjectivists, one for the frequentists, as my Xmas present to you all. Richard Gill (talk) 15:37, 1 January 2011 (UTC)

We wish to calculate numerical value of the conditional probability that the car is behind door 1 given that the player chooses door 1 and the host opens door 3 to reveal a goat. We first calculate the value of the probability that the car was originally placed behind door 1. This is 1/3 we all agree.

We then show, using a symmetry argument, that the numerical value of the conditional probability that the car is behind door 1 given that the player chooses door 1 and the host opens door 3 to reveal a goat must be equal to the value of the probability that the car was originally placed behind door 1. This gives us the answer to the question that we wished to know.

So, yes, I do and have always understood that the initial probability is a different concept from the conditional probability but, as I simply wish to calculate its value, this fact does not trouble me.

We thus use the easily calculated value of one thing to calculate the value of another, harder to calculate, thing, which is what Gerhard says above. There seems to be an attempt to add a non-existent layer of complexity to this problem.

The question that we are answering is 'what is the conditional probability that the car is behind door 1 given that the player chooses door 1 and the host opens door 3 to reveal a goat'. By this is meant 'what numerical value does this probability have?', not, 'What does this concept mean?'. We are therefore free to use any method that suits us to obtain the correct answer. Martin Hogbin (talk) 16:08, 1 January 2011 (UTC)

We're going round in circles. This has all been explained to you. As you say yourself: we want to calculate the conditional probability. That's all that counts. The way this is performed is unimportant. Using the symmetry does not turn this into the simple solution. The simple solution simply does not calculate any conditional probability, and moreover uses a logically wrong argument. Nijdam (talk) 16:34, 1 January 2011 (UTC)

The simple solution does calculate the correct value for the required conditional probability. In what way is this incorrect? Martin Hogbin (talk) 16:49, 1 January 2011 (UTC)

No Martin, do not say things without verifying. I did say just 4 lines above, that the simple solution does not calculate, not intends to calculate any conditional probability. So, why then do you write this?? Nijdam (talk) 17:25, 1 January 2011 (UTC)

Important sign: symmetry. Did I get that correct:
The simple solution gives the correct value for the required conditional probability, as long as that conditional probability is correctly based on symmetry?  Gerhardvalentin (talk) 17:06, 1 January 2011 (UTC)

Sorry Gerhard, you're sympathetic, but you do not understand much of probability theory, and mutatis mutandis, not much of the MHP. Nijdam (talk) 17:27, 1 January 2011 (UTC)

The simple solution tells us that (unconditional, overall) Pws is 2/3. Symmetry (in the symmetric case) tells us that the six conditional Pws's are all equal. The law of total probability tells us they must all equal the unconditional Pws, hence are all equal to 2/3. This shows us that always switching not only beats always staying (overall successrate 2/3 vs 1/3) but also that it beats any mixed strategy. If you just want to compare "always staying" with 'always switching" the simple solution is quite enough. If you want to show that "always switching" beats everything, you will need to look at the conditional probabilities. Which are not difficult to find, thanks to symmetry. On the other hand, no-one in their right mind would ever imagine that mixed strategies make any sense at all, so going the full Monty and proving optimality of "always switching" could be considered an academic luxury by non mathematicians. On the other hand, every mathematician knows that the standard and foolproof way to find the optimal solution is by conditional probability, and by symmetry, this conditional probability is child's play to find. So it is all not a big deal, as long as no-one insists either on being excruciatingly pedantic, nor on only using language which their great-grandmother who never went to school could understand. Richard Gill (talk) 19:00, 1 January 2011 (UTC)

Nijdam, here is one of the 'combining doors' simple solutions given in the article:

"Monty is saying in effect: you can keep your one door or you can have the other two doors." The player therefore has the choice of either sticking with the original choice of door, or choosing the sum of the contents of the two other doors, as the 2/3 chance of hiding the car has not been changed by the opening of one of these doors. [my bold]

No, Monty is saying: You have chosen door 1, I have shown the car is not behind door 3, would you prefer door 2?Nijdam (talk) 00:57, 9 January 2011 (UTC)

It would seem to me that the intent of this statement is to answer the question of what the probability of the car being behind the remaining door would be 'given that the host has opened either unchosen door (door 2 or door 3) to reveal a goat'. Would you not agree? Martin Hogbin (talk) 18:39, 1 January 2011 (UTC)

The combined door solution, interpreted in the right way, is equivalent to a form of the simple solution. It may be interpreted as calculating the unconditional probability and hence addressing the "unconditional" form of the MHP (if this may be called MHP anyway), i.e. the form in which the player is asked to switch, even before she has made her initial choice. I would much prefer if you react on my comment of 17:25. Nijdam (talk) 19:02, 1 January 2011 (UTC)

I do not understand what you mean by, 'The simple solution simply does not calculate any conditional probability'. Which simple solution do you mean? Martin Hogbin (talk) 21:38, 1 January 2011 (UTC)

You did read the article, did you? Nijdam (talk) 23:12, 1 January 2011 (UTC)

The article has several simple solutions. Do you mean vos Savant's solution as given in the article? Martin Hogbin (talk) 00:36, 2 January 2011 (UTC)

Martin wrote:

"I do not understand what you mean by, 'The simple solution simply does not calculate any conditional probability'. Which simple solution do you mean?"

Response from Richard

Let me try to answer.

The quizmaster will certainly open door 2 or 3 and reveal a goat. So conditioning on that is not conditioning at all. The probability the car will be behind the other door to the door opened by the quizmaster is 2/3. On the other hand, the events "quizmaster opens door 2", and "quizmaster opens door 3", are not certain. In fact they're complementary. It's true that 2/3 = P( car behind other door) = P( car behind door 3 | host opens 2 ) x P( hosts opens 2 ) + P( car behind door 2  | host opens 3 ) x P( host opens 3).  That is an application of the law of total probability. We need to do some more work to find out the value of P( car behind door 3 | host opens 2 ) or of P( car behind door 2 | host opens 3 ). For instance, an appeal to symmetry and some careful thought is enough to convince us that in the symmetric case, both these conditional probabilities are 2/3. However we cannot say that "the simple solution computes them". More brain work is needed to deduce their values.

So the answer to Martin's question is "Yes" to the question of the probability given the host has opened either door (2 or 3) (conditioning on a probability 1 event), but "No" to the question of the probability given that the host has opened door 2, and also "No" to the question if the probability given the host has opened door 3.

It all depends on whether the "or" between door 2 and door 3 is part of the description of one event, or if it actually intends us to talk about two probabilities given two different events. Ordinary language can be ambiguous. That's why one has to be very careful in formulation of statements about probabilities. Unfortunately these subtleties can be completely lost on some amateurs and totally confuse others (I do not refer to present company). Writers about MHP have to know more about probability than their intended readers. Richard Gill (talk) 09:21, 2 January 2011 (UTC)

But, in practice, as demonstrated by the current Wikipedia article, the only way to communicate all this to the reader relies on changing the problem by eliminating the 50/50 host premise (!), and then arguing that hypothetically, this might in some way make a difference. What a bunch of BS. Glkanter (talk) 10:17, 2 January 2011 (UTC)

@Glkanter, we both agree that the current Wikipedia article is overweight and biased. And what I wrote above does not introduce or eliminate any controversial premises. It offers a short and I hope clear argument why both unconditional and conditional probabilities are 2/3 under the usual symmetry assumptions. Hence that conditioning on a-door being opened gives the same answer as conditioning on a specific door being opened. Do you understand? Richard Gill (talk) 08:26, 4 January 2011 (UTC)

Richard, thanks for your response. I am not sure if the point you make is the one that Nijdam is making (perhaps, Nijdam, you could say whether Richard's point is the one you are trying to make). I have suggested that we add some extra (unobtrusive) text to the simple solutions to make clear that, for the conditional probabilities, 'More brain work is needed to deduce their values'. Nijdam has not supported this proposal, so I assume the point that he is making must be a different one. Martin Hogbin (talk) 10:32, 2 January 2011 (UTC)

Actually Richard I think your point does have a weakness, which leads to the same mistake that Morgan originally made, and this is to treat the three unknown distributions (producer's initial door choice for the car, player's initial door choice, and the host's door choice) differently. By starting with, 'Let's fix the player's initial choice as door 1' you have already made the decision that the car must be randomly placed, otherwise we could not fix the player's initial choice. Having made this decision you should logically be forced to make the same decision for the other unstated distributions, specifically the host door choice. Having done this, it no longer makes much sense to refer to door numbers at all. If we can fix the player's original choice we can ignore the host's door choice. I am not saying that you are wrong but the way you have put things can easily lead you into an erroneous line of thinking. Martin Hogbin (talk) 10:44, 2 January 2011 (UTC)

I agree that I am assuming that the car's location is uniform random. This could be a frequentist's given (because we know the quiz-team hides the car at random) or a subjectivist's expression of indifference to the door numbering. I disagree whether the quiz-master's choice should now be taken as uniform random or not. This will depend on our frequentist/subjectivist stance. But in either case it doesn't matter, as Morgan et al. show and as Gerhardvalentin continually reminds us: it is never disadvantageous to switch, and often disadvantageous not to, even if there is any (unknown) host-bias (provided the location of the car is uniform random! But otherwise not necessarily).

I could have written out the argument keeping the initial choice random, and not even necessarily uniformly random; Nijdam would like that. It just costs longer formulas with six instead of two configurations to be considered. The argument goes through unchanged. Again: if there is no host-bias and the location of the car is uniform random, all six conditional probabilities of winning by switching given door chosen by player and door opened by host are equal, hence equal to their weighted average, 2/3. Note that in all six conditional probabilities we have conditioned on the player's initial door choice. So it does not make any difference how that is chosen (uniformly or not, random or not). All of the 6 conditional probabilities are determined "host-side". The player's choices do not influence them. So we only need symmetry on the host side to get equality. The 6 weights do depend on player-side and host-side probabilities together. But it doesn't matter if they're equal or not. They add up to 1 anyway.

I agree that if everything is uniform then we have full symmetry and we can argue in advance that specific door numbers are irrelevant. From that point on we can follow the simple solution and we know it is optimal since we know (and said in advance) that there is no way to improve it.

I also have frequently pointed out that if we know nothing, and don't wish to use subjective probability, then a wise course of action is to choose our door initially uniformly at random and then switch. The simple solution tells me my (unconditional) success chance is 2/3 and the minimax theorem shows this can't be beaten. No assumptions at all are made on host behaviour nor on our knowledge or ignorance concerning host behaviour. Whatever the host does, we have our 2/3 guarantee of going home with the car. And because we chose our door at random and *not* by our lucky number, we won't feel foolish when (1/3 of the time) we switch and lose. By the way, it we are planning to switch anyway, and if we believe in our powers of extra-sensory perception, we should make our initial choice by our *unlucky* number: we should pick the door least likely to have the car behind it.

It's all written out in Gill (2011). I'm already getting fan-mail from colleagues all over the world for my fresh and refreshing take on MHP, which is of course gratifying for me! Richard Gill (talk) 09:01, 4 January 2011 (UTC)

Further response to Nijdam

Nijdam, is the point you are making that the simple solutions given in the article do not make explicit that they are intended to be solutions to the conditional problem, in particular, they do not mention door numbers. Is this a good description of your point or has Richard understood it better above? Martin Hogbin (talk) 10:45, 2 January 2011 (UTC)

Well, Richard have said almost all. Of course he did not give a complete analysis of the MHP, he just explained you what was needed for you to understand the difference between the unconditional and the conditional solution. I think he did not want to dwell by the necessity of some assumptions. Instead of trying to understand what he wants to show you, you write about the distributions, what has nothing to do with the point you have to understand. Nijdam (talk) 20:56, 2 January 2011 (UTC)

What puzzles me is that, given that the simple solutions do not compute a conditional probability without additional thought, you have not supported my suggestion to add some text to them to show how, with a little additional very intuitively obvious logic, the conditional probability can be obtained from the simple solutions. Martin Hogbin (talk) 23:41, 2 January 2011 (UTC)

Have some patience, I said already I come to this. For the moment, your deduction is logically false. The simple solution may be obtained from the conditional, but not the other way around. The conditional solution cannot be obtained from the simple solution (as such of course). The simple solution, extended with some extra argument may give the conditional solution, of course. With the right extension it may give any solution, even the proof of Pythagoras' theorem. Nijdam (talk) 10:17, 3 January 2011 (UTC)

So exactly what additional argument do you consider to be the minimum necessary to make the simple solutions solve the conditional problem? Martin Hogbin (talk) 11:31, 3 January 2011 (UTC)

Let me guess Nijdam's response: it will be that the simple solution never solves the conditional problem. The simple solution sets out to compute the unconditional probability, full stop. Nijdam is using the word "solve" in a more narrow sense than you, Martin. This is the difference between mathematician's and, say, physicist's or engineer's language. Richard Gill (talk) 09:22, 4 January 2011 (UTC)

I think you may well be right Richard, but the reason has nothing to do with mathematicians and physicists. To show that two calculations must give the same result and then use the easier method of calculation to obtain the desired result is a well known and well respected mathematical technique. In fact it is probably used by mathematicians more than anyone else. To use a symmetry to show the equivalence of two calculations is particularly common, indeed it was a mathematician, Boris, who first pointed out the symmetry. Neither solution is that rigorous, as Boris also pointed out.

To stick resolutely on this minor point is not, in my opinion, in the spirit of cooperative editing, bearing in mind that we can discuss the whole subject in detail later on in the article. There are some her who do not want any additions to the simple solution but I am trying to find an acceptable compromise. Martin Hogbin (talk) 10:34, 4 January 2011 (UTC)

I like the compromise you suggested, Martin. And anyway, wikipedia is about reporting what is "out there" in reputable published sources, not about what any particular editor believes to be the truth. But to do good editing it helps to understand the mathematical truth and to understand the different cultures of "problem solving" within professional mathematics and in ordinary recreational puzzle-solving. It would be interesting to learn what Martin Gardner thought of conditional versus unconditional solutions to MHP since he is someone who probably understands both worlds and can communicate in both worlds and between them. Richard Gill (talk) 13:04, 4 January 2011 (UTC)

I do not like the way you talk. I have repeatedly explained to you, and in fact Richard just some lines above says the same, that the simple solution SETS OUT TO CALCULATE THE UNCONDITIONAL PROBABILITY. Hence (simple logic) does not calculate the needed conditional probability. Hence is wrong. Symmetry has nothing to do with this. The way things are calculated is UNIMPORTANT. It is not about HOW things are calculated, but WHAT is calculated. Do you have difficulty in understanding this?? Cooperative editing from your side would be understanding, accepting this! And once and for all, never mention it again. Nijdam (talk) 11:56, 4 January 2011 (UTC)

But it is not clear, Nijdam, that MHP *must* be solved by conditional probability. It is not even clear what probabilistic assumptions should be made, if any. In fact, different sources make different assumptions and derive different "solutions" based on those assumptions. I am not aware of any reliable source on the mathematical statistical side, except perhaps for Gill (2011), which explicitly gives a rationale why we ought to go for a conditional solution. Different sources give different reasons for switching. As I point out in my article, the simple solution gives a good reason for switching under minimal assumptions. The conditional solutions give better reasons for switching but under stronger assumptions, hence are more restricted in scope. MHP is not the exclusive property of one particular branch of science. It is in the public domain. All interpretations and all logically correct analyses are legitimate. Richard Gill (talk) 13:04, 4 January 2011 (UTC)

Please Richard, let's not mix things up. I appreciate your comment above, and I'll try to respond to it, but has no connection to the point Martin is making over and over, although I explained him there is no point. Symmetry may be used to calculate the conditional probability in an easy way, but the intention has to be to calculate such a probability. As you said yourself does the simple solution not calculate the conditional probability. So if one wants to use the symmetry, he is not busy with the simple solution. I'm really getting tired of repeating this for the I don't what time. Nijdam (talk) 17:36, 4 January 2011 (UTC)

You are right Nijdam, we should separate the separate issues.. In my defense let me just say that Martin objected to me "fixing" the player's choice, saying that this implied I was making certain assumptions on the host-side. I needed to respond to that side-issue. Part of my response was to point out that your insistence on solving MHP by conditional probability, though certainly shared by many writers from statistics and probability, is not universally accepted either. All solutions seem to me to be relative to what is felt to be an adequate formalization of the question and what is felt to be adequate answer in different scientific cultures. Just because MHP often features in introductory statistics texts, and possibly was born there, does not mean that it is "owned" by the priests of a particular cult. And if the priests of a particular cult think they have something important to say about MHP which most people miss, they have to give good reasons why people should listen to them. (I think there are good reasons to promote the conditional solutions, but we are not doing very well in getting these across to the non-specialists. At the same time, I think the simple solutions are also of greater importance than the promoters of those solutions seem to believe, since they make weaker assumptions hence have wider applicability). Richard Gill (talk) 18:29, 4 January 2011 (UTC)

Acceptable formulation

Due to the obvious symmetry in the problem (NB we have to explain the standard assumptions before), the probability for the chosen door 1 to hide the car has the same value 1/3 before the player makes her choice and after the host has opened door 3. Hence at the moment of decision the remaining door 2 has probability 1-1/3=2/3 to hide the car. Nijdam (talk) 12:21, 4 January 2011 (UTC)

Would you object to this being put in more reader-friendly and less obtrusive language? We are talking about the 'Simple solutions' section, which is written for the general, non-expert, reader. The whole thing can be explained later in full detail. Martin Hogbin (talk) 13:18, 4 January 2011 (UTC

Is this more reader friendly?: As the car is placed randomly, the car is with probability 1/3 behind the chosen door. It may be intuitively understood, and it can be proven, that the host opening a door with a goat does not influence this value, hence after the door with a goat has been opened, the car is also with probability 1/3 behind the chosen door. As the only alternative is the remaining closed door, the car is behind this door with probability 2/3.

Martin, I do not agree with your criticism. And +1 to W. Nijdam. I fully appreciate his proposal as unequivocal and clear in its content. Reader-friendly formulation is secondary. Gerhardvalentin (talk) 13:36, 4 January 2011 (UTC)

Can we please take this to the mediation page? There's more to object to here than how reader-friendly the wording is, and I'd really rather discuss it there than here. -- Rick Block (talk) 16:32, 4 January 2011 (UTC)

Please do. And for the wording: I gladly leave this to a native speaker. Nijdam (talk) 17:25, 4 January 2011 (UTC)

Here, by courtesy of Martin, we are discussing The Truth. On the mediation page people discuss how to resolve editorial conflicts concerning the MHP page. I don't see anything wrong in side discussions which help interested editors to better understand what the sources are talking about, and the different forms which are used in different scientific cultures. Richard Gill (talk) 18:10, 4 January 2011 (UTC)

Ah, The Truth. So is the "Monty forgets" variant symmetric? My point is that symmetry by itself is not ensuring that the "obvious probability", the prior probability P(car behind player's door)=1/3, is the same as the "unconditional" posterior probability, i.e. P(car behind player's door|the host has opened a goat door) - but is rather ensuring this "unconditional" posterior probability is the same as any of the "conditional" posterior probabilities, e.g. P(car behind player's door|player picked door 1 and host opened door 3). I believe Martin's understanding of the MHP is that the crux of the issue is whether the prior probability P(car behind player's door) is the same as the posterior probability P(car behind player's door|the host has opened a goat door) but Nijdam's understanding is that the crux of the issue is whether the prior probability is the same as a specific conditional probability such as P(car behind player's door|player picked door 1 and the host opened door 3). If the reason people think the answer is 50/50 is because they know with certainty that the "probability" the car is behind door 3 is 0 after the host has opened this door, then (IMO) Nijdam's understanding is the correct one - since the posterior "unconditional" probability P(car behind player's door|the host has opened a goat door) is identically the same as the prior probability (because "the host has opened a goat door" is a null condition). With this null condition, there is no paradox - the probability of all doors starts and ends 1/3 (including doors 1 and 3 in the example case where the player picks door 1 and the host opens door 3!). Only with a condition are we faced with the prospect of looking at two closed doors and an open door showing a goat. -- Rick Block (talk) 19:46, 4 January 2011 (UTC)

Let X be the number of the door chosen by the player, let H be the number of the door opened by the host, and let Y the number of the remaining door. Let C be the number of the door hiding the car. Prob(C=Y)=2/3 because C is never H, thus the events {C=X} and {C=Y} are complementary, and therefore Prob(C=Y) = 1-Prob(C=X) = 1-1/3 = 2/3. This is a version of the simple solution, correctly giving 2/3 as the unconditional probability that switching gives the car. I did not condition on anything (in the probabilistic sense) to deduce this fact. So I don't understand what Rick means by saying "only with a condition are we faced with the prospect of looking at two closed doors and an open door showing a goat". Richard Gill (talk) 00:28, 5 January 2011 (UTC)

To make sure everything is understood in a proper way, I want to remark that this remaining door Y (a random variable) is not the same as the remaining door in the (our) MHP. In our example i.e. is door No. 2 the remaining door (a fixed number).Nijdam (talk) 13:12, 5 January 2011 (UTC)

W. Nijdam: "Y is a random variable". But you can read "Prob(C=Y) = 1-Prob(C=X) = 1-1/3 = 2/3" also as follows:
Prob(C=y) = 1-Prob(C=x) = 1-1/3 = 2/3,   that means:

Prob(C=door#2) = 1-Prob(C=door#1) = 1-1/3 = 2/3   (is it that what you want to know?)  –  Other possible variants:
Prob(C=door#3) = 1-Prob(C=door#1) = 1-1/3 = 2/3   (if door #2 has been opened)
and so on.   Gerhardvalentin (talk) 17:05, 5 January 2011 (UTC)

Sorry Gerhard, this all makes no sense. Indeed is, as Richard wrote: Prob(C=Y) = 1-Prob(C=X) = 1-1/3 = 2/3" , but what you make out of it is rubbish. On the contrary is P(C=y)=1/3 for y=1,2,3. Furthermore is P(C=2)=1-P(C=1 or C=3). So, what do you want to say? Nijdam (talk) 21:11, 5 January 2011 (UTC)

Door#3 is open now, showing a goat, and P(C=door#1) is unchanged 1/3.   Gerhardvalentin (talk) 22:12, 5 January 2011 (UTC)

Well, Gerhard, believe it or not, also P(C=door#2)=P(C=door#3)=1/3. Nijdam (talk) 21:33, 7 January 2011 (UTC)

Please help me get what you are saying. Things have progressed, meanwhile the guest did choose door#1 out of three doors, and then the guest sees the host opening another door. And he sees that the host just has opened door#3 showing a goat, that's the actual situation now. Are you really saying that at this point the probability that the car is behind the open door#3=1/3? Thank you for your help, W.Nijdam. Gerhardvalentin (talk) 13:51, 8 January 2011 (UTC)

Symmetry on the host-side (location of car, door opened revealing a goat) ensures that all six conditional probabilities

Prob( Car is behind "other door" | player chose Door x, Host opened Door y ),

for x, y any pair of different door numbers are equal. Thus

2/3 = Prob(Car is behind "other door")

= sum over all x,y Prob( Car is behind "other door" | player chose Door x, Host opened Door y )

times Prob( player chose Door x, Host opened Door y )

by the law of total probability, since the six events { player chose Door x, Host opened Door y } are mutually exclusive and exhaustive. Hence, calling the common value of the six conditional probabilities q,

2/3 = q times sum over all x,y Prob( player chose Door x, Host opened Door y ) = q times 1 = q

using again the fact that the six events { player chose Door x, Host opened Door y } are mutually exclusive and exhaustive.

The point I am making is that the symmetry argument which allows us to deduce the conditional probabilities from the unconditional makes explicit use of the fact that Monty never opens a door revealing a car; note that we use the law of total probability as well as symmetry. If you want to use symmetry to solve the forgetful Monty problem, you will have to make quite a few adjustments to the computations I just gave.

The symmetry argument is easier to write out when we first fix (or equivalently, condition on) the door chosen by the player. We only have to consider a partition of the sample space into two events then, instead of six. Richard Gill (talk) 00:16, 5 January 2011 (UTC)

It's not 2/3 & 1/3 if there are 4 doors, and Monty reveals 1 goat. All premises are required, equally. No more, no less. Glkanter (talk) 20:04, 4 January 2011 (UTC)

The unconditional probability that switching gives the car is 2/3 if and only if the original choice of the player is correct with probability 1/3. And for this to be true, it is necessary and sufficient that either the player's choice is uniform at random or the location of the car is uniform at random. But if you want the six conditional probabilities all to be 2/3 too, then you must assume the location of the car is uniform at random and the host-choice is uniform random (when he has a choice). So what premises you require depends on how strong a conclusion you want to get. Richard Gill (talk) 00:35, 5 January 2011 (UTC)

Speaking of 'Monty Forgets' or 'Random Monty', what kind of a game show is it when the host reveals the grand prize, ending the game prematurely? Glkanter (talk) 20:28, 4 January 2011 (UTC)

Note that Nijdam continually speaks of THE probability, at different time points. His picture is the following: random things happen in order, in time, and each time something happens THE probability distribution of the location of the car is updated (according to Bayes' rule, of course). We have: 1/3,1/3,1/3 - Player chooses Door 1 - 1/3,1/3,1/3 - Host opens Door 3 revealing goat - 1/3,2/3,0 - Player switches and Door 2 is opened revealing a ... - 1,0,0 or 0,1,0. For him we must compute THE probability distribution of the location of the car at the time the player must make his decision, and this is the conditional distribution of that location given the information which has been received so far: door 1 chosen, door 3 opened. What he didn't give us yet is a reliable source saying that this is what we MUST do and WHY we must do this. Also he didn't tell us where his assumptions of uniform distributions come from and whether they are subjectivist or frequentist. He doesn't mind how we compute the probability distribution but he insists that we do more than just conjure up some numbers from out of our hat: we have to justify those numbers. Saying that the unconditional probability that switching gives the car is 2/3, is not enough. But saying this and saying that therefore by symmetry of the host-side probability distributions and the law of total probability, the conditional probability of the same event given the specific door numbers chosen and opened is the same value 2/3, is enough.

His short argument above corresponds to splitting the "door opening" by the host into two steps: first a door is opened revealing a goat but without saying which door was opened, then the identity of the opened door is communicated. We have: initial situation - 1/3,1/3,1/3 - Player chooses Door 1 - 1/3,1/3,1/3 - Host opens a door revealing goat but keeping identity of opened door secret - 1/3,1/3,1/3 - Host divulges identity (Door Number 3) of the Door he has opened - 1/3,2/3,0 - Player switches and Door 2 is opened revealing a ... - 1,0,0 or 0,1,0.

I would rewrite Nijdam's short derivation as follows: The probability for the chosen door 1 to hide the car has the same value 1/3 before the player makes her initial choice, and after she has made her initial choice and the host has opened a door revealing a goat but without yet knowing which door has been opened: 2 or 3. By the symmetry of the host-side probability distributions, it is equally likely that door 2 or 3 is opened if the car is behind door 1, and it is equally likely that door 2 or 3 is opened if the car is not behind door 1. Hence the identity of the opened door, in our case, 3, gives no information about whether or not the car is behind Door 1 and therefore does not alter the probability the car is behind door 1: it remains 1/3. Hence at the moment of decision the remaining door 2 has probability 1-1/3=2/3 to hide the car.

At the crucial step I am here using Bayes' rule in the odds form. Just before the identity of the opened goat door is divulged, the odds on Door 1 hiding the car are 1:2. The probability Door 3 was opened given the car is behind Door 1 is 50%. The probability Door 3 was opened given the car is not behind Door 1 is 50%. The likelihood ratio is therefore 1:1. The posterior odds are therefore unchanged at 1:2. Note that the two probabilities of "50%" each come from a different component of the host-side probability distributions. In case the car is behind Door 1 we use the unbiased host premise. In case the car is not behind Door 1 we use the initial uniform distribution of location of the car, conditioned on "not Door 1". Richard Gill (talk) 08:58, 5 January 2011 (UTC)

Basics

I think, the discussion basically comes down to the question whether the simple solution, i.e. the solution without any reference to the conditional (posterior if you like ) probability, can be considered a correct solution to the MHP. Here the MHP is understood to be the version in which the player is offered to switch after the host has opened the goat door. IMO it is not; it produces the right advise: "switching is to your advantage", but based on the wrong arguments. And then: the version of the simple solution that concludes that the car must be with probability 2/3 behind the remaining door, because for the opened door the probability is 0, and the chosen door has probability 1/3 due to the random placement of the car, is completely wrong, and should be banned or at least be exposed as such. Nijdam (talk) 13:27, 5 January 2011 (UTC)

LOLZ. That's your conclusion from all that discussion in a section called "Acceptable formulation"? Glkanter (talk) 13:55, 5 January 2011 (UTC)

Questions allowed? Please who can tell me whether the following variant of the sentence above is correct or is incorrect ( I have added bold, underlined words to the aforementioned full sentence):

"the version of the simple solution that concludes that the car must be with probability 2/3 behind the remaining door, because for the opened door the probability is 0, and the originally chosen door still has probability 1/3 due to the random placement of the car and due to the unbiased opening of door #3, is completely wrong, and should be banned or at least be exposed as such."
Who can tell me the "TRUTH"?   Thank you all!  Gerhardvalentin (talk) 14:58, 5 January 2011 (UTC)

This sentence of yours is correct, be it that the independence or car placement and choice of door should be counted for, but it is not a variant of what is understood as the simple solution. Nijdam (talk) 21:32, 5 January 2011 (UTC)

Please, in this section, just about the basics. Nijdam (talk) 21:24, 6 January 2011 (UTC)

Topic??

@Nijdam: define C = door hiding car; X = door initially chosen by player; H = goat-door opened by host; Y = remaining door (door to which player is offered to switch). C must equal exactly one of X, H, and Y; it never equals H; therefore C must equal exactly one of X and Y. The events {X=C} and {Y=C} are therefore complementary and hence Prob(Y=C)=2/3 if and only if Prob(X=C)=1/3. What is "completely wrong" with this argument? - apart from your insistence that what we really ought to be computing is Prob(Y=C|X=1,H=3), not Prob(Y=C).

"What we ought to be computing" is a matter of opinion - editors disagree and sources disagree. Selvin himself seems to find both quantities equally interesting and equally valid as solutions. Rosenthal's argument that we ought to be computing the conditional probability is pretty feeble. Carlton gives no reason at all for his preference. Morgan et al. give no reason at all. The only source as far as I know which explicitly gives a reason behind the dogma is Gill (2011).

Are you telling me that my computation of Prob(Y=C) is incorrect? Or are you just telling us that in your opinion, MHP is solved by computing Prob(Y=C|X=1,H=3), not Prob(Y=C)? You are welcome to your opinion of course, but editors' personal opinions are not supposed to play any role in wikipedia articles. Richard Gill (talk) 22:02, 5 January 2011 (UTC)

You've shown me this several times before. What is the purpose? Note that your rv, Y, is something different than the remaining closed door in the MHP, a constant in each possible situation. Nothing wrong with your computations, I do not expect otherwise. But why do you do these calculations, that's the question. Nijdam (talk) 21:24, 6 January 2011 (UTC)

My purpose here was to give a short mathematically rigorous and at the same time intuitively transparent proof that switching gives the car with unconditional probability 2/3, if and only if staying gives the car with unconditional probability 1/3. Y is the number of the door which remains closed after the player's choice and the door opened by the host. It is not fixed in advance. It becomes fixed, once X and H are fixed. What's the problem? Richard Gill (talk) 21:32, 6 January 2011 (UTC)

May be it is the beer, but Y is a random variable and never gets fixed, Yes, as you say, when X and H are fixed, then also Y is fixed, but you may wait till the end of times, X and H are also rv's, hence never will be fixed. I know what you want to say, but you didn't. Nijdam (talk) 22:16, 6 January 2011 (UTC)

Maybe it is the beer, maybe it's the wine, but in my opinion (in my way of thinking) a random variable can become fixed in time, in the sense that as information becomes available and the probability distribution is continually updated by Bayes' rule, its probability distribution can become degenerate. This seems to me to be a common stochastic process (filtration, history) point of view. But it is just words, used to visualize the formal mathematical model. I think we agree on the mathematical facts. Richard Gill (talk) 16:12, 7 January 2011 (UTC)

Be my guest. It's a way of describing what's happening. Instead of conditional probabilities, you have to speak of updated probabilities. What's in a name. It doesn't however change a bit. The simple solution also do not calculate your updated probabilities. Nijdam (talk) 21:46, 7 January 2011 (UTC)

Let A, B and C be any three events. Note that P(A|C)=P(A&C)/P(C)=P(C|A)P(A)/P(C) and P(B|C)=P(B&C)/P(C)=P(C|B)P(B)/P(C). Divide the "A" formulas by the "B" formulas, P(A|C)/P(B|C) = { P(A)/P(B) } . { P(C|A)/P(C|B) }. Posterior odds equals prior odds times likelihood ratio, Bayes rule.

We can generalize Bayes' rule to an evolving history where events C1, C2, C3 in turn are taken account of:

P(A|C1 C2 C3)/P(B|C1 C2 C3) = { P(A)/P(B) } . { P(C1|A)/P(C1|B)} . { P(C2|A C1)/P(C2|B C2) } . { P(C3|A C1 C2)/ P(C3|B C1 C2) }.

BTW this basic idea is one of the secrets of the Kalman filter, the mathematical equations of systems theory, without which we wouldn't have landed on the moon.

Now consider the evolving history of the game: player chooses door (C1) - host opens goat-door (C2) - player learns number of door opened by host (C3). As the history unfolds the odds between any particular pair of statements must be continually updated according to Bayes' rule. Let A={car is behind Door 1}, B={car is not behind Door 1}. Initially the odds between A and B are 1:2.

The first piece of history is unveiled (the first event "C", C1): the player chooses door 1. The probabilities of A and B do not depend on C so the odds between them remain 1:2.

The next piece of history unveiled (the next event "C", C2) is that the host opens one of the other doors, as yet unspecified. He does this with probability 1 both when the car is behind door 1 and the player chose door 1, and when the car is not behind door 1 but the player did choose door 1. So the likelihood ratio for this piece of "information" is 1/1=1 and the odds remain 1:2 on the car being behind door 1.

The next piece of history unveiled (the next event "C", C3) is the identity of the opened goat-door. In scenario A (car behind door 1) we know car is behind door 1, player chose door 1, and host opened a door revealing a goat. The door he opens is Door 3 with probability 0.5 (no host-bias). In scenario B (car not behind door 1) we already know player chose door 1 and the car is not behind door 1, the host opens a goat-door. He doesn't have any choice since he has to open door 2 or 3 and the car is behind door 2 and door 3 each with probability 0.5 since it isn't behind door 1 (initial location of car is uniformly distributed). The door the host opens is therefore Door 3 with probability 0.5. The likelihood ratio is 0.5/0.5=1 and the odds remain 1:2 on the car being behind Door 1.

The difference between the simple and the conditional approaches is quite simply whether or not they explicitly take note of the last step: the revealing of the number of the door opened, after we already know the number of the door chosen by the player and that the host has opened an unspecified goat-door. The final step in the history - the final piece of information given to the player - the specific number of the door opened by the host - turns out actually not to give any information about whether or not the car is behind Door 1. (Of course it does give information about whether or not the car is behind Door 3!). The odds for Door 1 versus NOT Door 1 remain 1:2 throughout the whole history, in fact none of the steps give any information about this question, in the sense of changing the odds.

I could have gone through this story considering the odds on Car behind Door 1 : Car behind Door 2 : Car behind Door 3. They start out as 1/3:1/3:1/3. The player's choice does not alter them, and the information that the host has opened another door revealing a goat doesn't change them. However the probabilities that he opens Door 3 given the player chose Door 1 and the car is behind Door 1, 2 or 3 are 0.5, 1, 0; so the posterior odds on Car behind Door 1 : Car behind Door 2 : Car behind Door 3 are 0.5 : 1 : 0 = 1 : 2 : 0.

Considering Door 1 versus Not Door 1 is a clever simplification which brings the simple and the conditional solution very close together. But of course it gives the same final answer as considering Door1:Door2:Door3. Richard Gill (talk) 22:29, 5 January 2011 (UTC)

Richard, I agree with what you have said, particularly your statement starting, 'The difference between the simple and the conditional approaches...'. I assume that you are using 'simple' and 'conditional' a sense specific to this discussion. I reality both calculations involve conditional probability. In the first case we have the condition that the player has chosen door 1 ( he could have chosen any door) and in the second case we have an additional condition. Do you agree? Martin Hogbin (talk) 01:04, 6 January 2011 (UTC)

Simple solutions like Carlton's and Monty Hall's are conditioned on the 100% likelihood that the host reveals a goat. The decision tree that has been banned from the article shows that. They are indifferent as to which door is opened. Glkanter (talk) 02:23, 6 January 2011 (UTC)

@Martin: I was indeed using the words "simple" and "conditional" to refer to the two main classes of solutions to MHP, and moreover for me "conditional" refers to conditional probability. One can say that conditioning on a certain event is also conditioning, but I think it is better to try to restrict it to "serious" conditioning when one conditions on events which are not certain, so that at least some probabilities will change by doing so.

One can give a simple solution without conditioning on the initial door choice. Define C = door hiding car; X = door initially chosen by player; H = goat-door opened by host; Y = remaining door (door to which player is offered to switch). C must equal exactly one of X, H, and Y; it never equals H; therefore C must equal exactly one of X and Y. The events {X=C} and {Y=C} are therefore complementary and hence Prob(Y=C)=2/3 if and only if Prob(X=C)=1/3. This little solution leaves quite open whether we are thinking of X or C or both as random. If you want it to work for X fixed (and equal to 1, say), you have to assume C is random and Prob(C=1)=1/3. You can also use this argument from Monty's point of view, for him C is fixed (1, say) and the player's choice X is uniform random.

@Glkanter: indeed there is a decision tree representation for the simple solution too. And indeed the reason that the initial probability that the door chosen hides the car is not changed when the quizmaster reveals a goat (but without yet saying which door he pulled it from) is because conditioning on a certain event does not change any probabilities.

Yes, it's this indifference (100% probability of revealing a goat) to which door is open that makes the simple solutions work. The simple decision tree demonstrates that the contestant has *not* made his choice before the goat is revealed, and that the solution is *not* an 'average', or 'overall probability' of anything, except the average probability of door 2 or door 3 being opened, which are known to be equal (each a likelihood of 2/3 of having a goat, same as the contestant's door, due to the original distribution of the car and goats). That decision tree shows that Nijdam's arguments are without merit. Brushing this off *because* of the 100% condition is unwarranted. Glkanter (talk) 10:51, 6 January 2011 (UTC)

Here I am afraid I disagree. The 2/3 of this simple solution is the average over the success chances when Door 2 is opened, and when Door 3 is opened. Those two possibilities are equally likely, but that is not the crucial point. The crucial point is that the probability Door 1 was hiding the car is not changed when we receive the information whether it was Door 2 or Door 3 which was opened. In both cases it is 2/3, and their average is 2/3. But you don't know that it is 2/3 in both cases from just studying the decision tree which you authored. You need to give an argument for this fact. One argument is symmetry, another argument comes from the final contribution to the odds ratio for Door 1 versus Not Door 1, 0.5/0.5. The 0.5 in the numerator (upstairs) is the probability Door 3 is opened given the player chose door 1 and the car is behind door 1, the 0.5 in the denominator (downstairs) is the probability the car is behind door 2, given that it is Not behind door 1. Richard Gill (talk) 20:35, 7 January 2011 (UTC)

There's nothing else I can say that I haven't already said numerous times. Except this: I disagree with your arguments and conclusions, and many reliable sources give a solution that is contradictory to the 'requirements' you seem to lay out. Glkanter (talk) 20:50, 7 January 2011 (UTC)

My point of view is that we have a number of different correct derivations of different probabilities under different conditions. It is up to the user to choose which assumptions they are prepared to make and therefore which conclusions they can buy with them. It is up to the user to decide what kind of probability notion they want to use. It is up to the seller to argue why it is worth paying the extra money for a Mercedes (conditional) when a Volkswagen (simple) seems good enough for most people.

What I like about the argument I gave with the three steps C1, C2, C3 and considering the odds on Door 1 : Not Door 1 is that you see how you the simple solution is obtained (at step 2) having used very little assumptions, while the conditional solution (at step 3) makes explicit use of both host-side uniformity assumptions. What I also like is the use of Bayes rule in the odds form. This makes conditional probability simple and intuitive! It means that one can give a full mathematically rigorous conditional solution in a couple of sentences of plain English - you don't need to work through big formula manipulations. It shows exactly what the "extra" of the conditional solution is. This is what good mathematics is about: replacing computations by ideas (Riemann, Hilbert). Richard Gill (talk) 08:45, 6 January 2011 (UTC)

@Gerhardvalentin: the C1, C2, C3 and Door 1 : Not Door 1 argument allows us to take account of host bias. We just have to change one of the two 0.5 probabilities into an arbitrary number between 0 and 1 (which of the two is changed, is important!). In the two extreme cases the final odds are 2:0 and 2:2 with the "no-host-bias" giving the usual intermediate 2:1. So switching is never wrong and therefore even if you don't know the host bias the answer is "switch". The unconditional probability you'll get the car is 2/3, the conditional probability is somewhere between 1/2 and 1. (This is the whole mathematical content of Morgan et al's work). Richard Gill (talk) 08:58, 6 January 2011 (UTC)

Different solutions

Richard, let do as you suggest above and not treat events which are certain, essentially the game rules, as conditions.

Do you agree then that, on that basis, we should start with a sample space including all the possible outcomes allowed under the game rules.

The next step should be, as you say above:

1) The player chooses door 1.

We should therefore condition our sample space on that basis first of all. Note that we cannot say that the players door choice is independent of the car placement unless we know that the car placement (or the player's choice) is random. As is most commonly done let us assume that both are uniform at random. Do you agree so far? Martin Hogbin (talk) 10:06, 6 January 2011 (UTC)

I prefer to keep all my options open. Let's agree there is a door hiding a car, a door chosen by the player, a (different) door opened by the host (revealing a goat), and a third door left over. Call them C, X, H, Y. Random variables taking values in the set of door numbers {1,2,3}. There are some structural relations between them: H is certainly different from X, and then Y takes the remaining value from {1,2,3}, different from both X and H. Also, H is certainly different from C. Everyone will agree to take C and X statistically independent of one another. That still permits either or both of them to be fixed (non-random) as well as random. The joint probability distribution of everything can be built up from the marginal distributions of C and of X (host-side and guest-side respectively), and the conditional distribution of H given C and X (host-side). Even if I originally assumed X random, I can condition (in the probabilistic sense) on X=1, say, if I want to. By independence the distribution of C does not change. I already built up my model by imagining a collection of conditional distributions over the values of h, Prob(H=h|C=c,X=x) for all c and x, so I can still put the model together with X=1 fixed.

It follows from the structural assumptions that Prob(Y=C)=1-Prob(X=C). And by independence, Prob(X=C)=Prob(X=1)Prob(C=1)+Prob(X=2)Prob(C=2)+Prob(X=3)Prob(Y=3). (Note that this relation is also true if X is fixed, e.g. Prob(X=1)=1, Prob(X=2)=0=Prob(X=3). A bit of algebra shows that if either X is uniform on {1,2,3} or if C is uniform on {1,2,3}, then Prob(X=C)=1/3. So it can be forced host-side, and it can be forced guest-side, that the initial choice is correct with probability 1/3. And when that is true, switching gives the car with probability 2/3.

This is the basis for the recommendation to the player coming from game-theory. The game-theoretic-savvy player has no interest in conditional probabilities since they involve host-side probability distributions over which he has no control. He just wants to have the best probability of coming home with a car. So he randomizes his initial choice and always switches. His success-chance is 2/3. The game-theoretic-savvy Monty, on the other hand, wants to keep as many cars as possible. So he completely randomizes the location of the car and he completely randomizes the choice of door to open when there is a choice. That way he prevents any player (e.g. a player with inside knowledge about the probabilities used in the randomizations host-side) from doing better than 2/3.

A passive player who just wants to see how the probabilities change in time as information is released will postpone making any decision as late as possible, because at least that way he is guaranteed that his decision will be optimal (optimal with respect to unconditional(!) probability of succes). This player presumably either uses subjective probability, or he is a frequentist and has been given some hard information about the procedures used host-side to hide the car and to open a door. If he knows frequentistically or knows subjectivistically that initially all doors are equally likely to hide the car he might just as well start by choosing door 1 because 1 is his lucky number. (If despite his beliefs of uniformity he is superstitious, he would be wiser to choose door number 1 because 1 is his unlucky number). Such a player just wants to see the probabilities unfold and he does this because he already "knows" that C is uniform random.

So yes, for this player it makes sense to start by conditioning on his actual door choice, X=1. By independence the distribution of C is not changed and it remains uniform. So his odds on the location of the car are still uniform, 1:1:1, after he has chosen this door.

Now the host opens a door and we hear a goat bleating, but the guest was not allowed to see which door it was yet. He just knows that it is a different door from number 1. The new information was going to happen certainly, under all three possible locations of the car, so his odds remain 1:1:1.

The host asks if he would like to switch to the "other door". If he must decide at this moment, his answer will be YES, because the odds that the car is behind "the other door" are now 2:1. As they always were. Prob(Y=C):Prob(X=C) = 1:2, both before conditioning on X=1, and after, and after also conditioning on the certain event that he would hear a goat bleating behind an as yet to him unknown door H different from X and Y.

If he doesn't have to decide now, he could say "but tell me first which door you opened". The host could then say, OK, H=3. The chance that the host would say "H=3" is different under the three hypotheses: C=1, C=2, C=3. The three chances are q, 1, 0, where q is the probability the host opens door 3 when he has a choice between 2 and 3. The posterior odds now become q:1:0 since the prior odds were uniform. Whatever q is, these odds support switching to door 2. At one extreme the car is now CERTAINLY behind Door 2. At the other extreme it is equally likely behind 1 or 2, so you may as well switch. In the case of a known unbiased host, or when your subjective assesment of the bias is completely indifferent regarding direction of bias, we get 0.5:1:0 = 1:2:0. Clearly he might just as well not have asked since he's going to switch anyway. This is Gerhardvalentines signature tune, and the content of Morgan et al's work. Richard Gill (talk) 14:28, 6 January 2011 (UTC)

My recommendation to wikipedia MHP page editors is to cut a large amount of the present maths formalism out of the page, in particular, out of the conditional solutions part of the page. Conditional probability is not difficult, and Bayes' rule in odds form is extremely intuitive and powerful. Emphasize the close connections between the conditional and unconditional solutions. There is nothing wrong with most authorities' derivations of the unconditional probability that switching gives the car. Don't criticise them, just report honestly what they deliver. Concentrate on the short sharp simple derivations which don't bring in assumptions which some people find discutable. Accept that there is a mathematical school of thought that says "you *have* to compute the conditional probability" (for instance, because only in this way is it guaranteed that your solution is optimal) but the step-by-step computation of the conditional probability shows that the last step, bringing in the information of the specific door number opened by the host, does not lead to a different decision. Just as one would expect. We know that always switching has overall success change 2/3, that always staying has overall success chance 1/3. It is pretty inconceivable that there could be anything better than 2/3. Proving it mathematically seems to me to be a bit of a luxury --- except in the mathematics class-room, where it is essential to pay some attention to that issue too. Richard Gill (talk) 14:44, 6 January 2011 (UTC)

+1. Yes, thank you. The MHP-paradox (Pws 1/2 or 2/3, odds 1:1 or 1:2) is foremost a "psychological problem" of approximation and assessment of chances and risks (YES or NO), not a flat "Mathematical probability puzzle" in the first line. Caracterized by completely contradictory positions, it is necessary to distinguish: Bare conditional probability theorems, based on differing audacious "assumptions" are used primarily for mathematical training purposes, and there they are doing quite well. Although sold under the so-called rubric "solving the MHP", it is less a "solving the paradox", but more about training opportunities in maths. And "en.WP" could finally lead the way as a pacesetter to a NPOV depiction. Gerhardvalentin (talk) 22:48, 6 January 2011 (UTC)

Based on your recommendation, Richard, do you agree with my proposal on the mediation page to eliminate paragraphs 2 & 4 from the 'Conditional solution' section? How about paragraph 1? Glkanter (talk) 16:59, 6 January 2011 (UTC)

The first paragraph is presently

The simple solutions show in various ways that a contestant who is going to switch will win the car with probability 2/3, and hence that switching is a winning strategy. Some sources, however, state that although the simple solutions give a correct numerical answer, they are incomplete or solve the wrong problem. These sources consider the question: given that the contestant has chosen Door 1 and given that the host has opened Door 3, revealing a goat, what is now the probability that the car is behind Door 2?

I would rewrite this paragraph, perhaps as the following:

The conclusion of the simple solution is that "always switching" beats "always staying": overall success-chance 2/3 versus 1/3. Some sources however are interested in something different: given that the contestant has chosen Door 1 and given that the host has opened Door 3, revealing a goat, what is now the probability that the car is behind Door 2? The reason for this more subtle and detailed inspection is that in principle it is possible that in some of the six possible situations (specific door chosen by guest, specific door opened by host) it would be better to switch and in other situations better to stay. If so, the overall succes-rate could be made better still than 2/3, the success-rate which is achieved by *always* switching.

After this I would compress all the remaining material of the section on "Conditional Solution" into one or two short paragraphs. Perhaps first of all I would report the symmetry argument, according to which, in the situation of no host-bias, all six conditional probabilities are equal to one another and hence, by the law of total probability, to the unconditional probability 2/3. After that I would perhaps do a Bayesian analysis on the lines of the discussion above: using the odds form of Bayes' rule I would show how the odds on the location of the car change as each piece of the history becomes unveiled, showing how the simple solution is obtained at the phase when we know a door is opened revealing a goat but don't yet know its identity, and how the further information of the identity of the opened door doesn't change the odds at all in the symmetric case, but anyway, cf. Morgan et al., doesn't change the decision whether it is best to switch or stay. Richard Gill (talk) 21:50, 6 January 2011 (UTC)

I would add some and write: The conclusion of the simple solution is that "always switching" beats "always staying": overall success-chance 2/3 versus 1/3, meaning that on the average 2/3 of all players will win the car. It is not clear however whether this result also holds for the player in the situation given in the problem. Some sources are therefore interested in something different: given that the contestant has chosen Door 1 and given that the host has opened Door 3, revealing a goat, what is now the probability that the car is behind Door 2? The reason for this more subtle and detailed inspection is that in principle it is possible that in some of the six possible situations (specific door chosen by guest, specific door opened by host) it would be better to switch and in other situations better to stay. If so, the overall succes-rate could be made better still than 2/3, the success-rate which is achieved by *always* switching. Nijdam (talk) 22:25, 6 January 2011 (UTC)

Yes, something like that seems to me to be the right motivation for going into the more tricky conditional probability stuff. Richard Gill (talk) 16:12, 7 January 2011 (UTC)

I don't suppose y'all would consider just removing the stuff that that doesn't apply to the 50/50 host MHP, and leaving the 3rd paragraph like it is? Glkanter (talk) 00:33, 7 January 2011 (UTC)

You're referring to the paragraph

The conditional probability of winning by switching given which door the host opens can be determined referring to the expanded figure below, or to an equivalent decision tree as shown to the right (Chun 1991; Grinstead and Snell 2006:137-138), or formally derived as in the mathematical formulation section below. For example, the player wins if the host opens Door 3 and the player switches and the car is behind Door 2, and this has probability (1/3)x1 = 1/3. The player loses if the host opens Door 3 and the player switches and the car is behind Door 1, and this has probability (1/3)x(1/2) = 1/6. These are the only possibilities given host opens Door 3 and player switches. The overall probability that the host opens Door 3 is their sum, and we convert the two probabilities just found to conditional probabilities by dividing them by their sum 1/3+1/6=1/2. Therefore, the conditional probability of winning by switching given the player picks Door 1 and the host opens Door 3 is (1/3)/(1/2), which is 2/3.

I would rewrite this as

The conditional probability of winning by switching given which door the host opens can be determined referring to the expanded figure below (is the figure needed???), or to an equivalent decision tree as shown to the right. It assumes that the player has already chosen Door 1. The switching player wins if the host opens Door 3 and the car is behind Door 2, and this has probability 1/3. The switching player loses if the host opens Door 3 and the car is behind Door 1, and this has probability 1/6. These are the only possibilities in which Door 3 is opened. The overall probability that the host opens Door 3 is their sum 1/3+1/6=1/2. Therefore, given the player initially chose Door 1, the conditional probability of winning by switching given the host opens Door 3 is (1/3)/(1/2), which is 2/3.

I would add to this paragraph a short discussion of the rationale for the conditional solution: that it explicitly makes use of all the information in the possession of the player, hence is guaranteed to generate the optimal overall success rate, which we thereby know is 2/3. This discussion could include the proof of the conditional result from the unconditional by symmetry and the law of total probability, because this elegant proof shows explicitly that the extra information (identity of door opened) does not change the chances that the car is behind Door 1. I would also have a section discussing the difference between the conditional and the unconditional solution, illustrated with the proof by step-wise updating by Bayes' rule in odds form. In that section I would show how the unconditional solution only makes use of the assumption that Door 1 hides the car with probability 1/3, and how the conditional result depends on the subtle balance of the 50/50 two host-side uniformity assumptions. At the same time I would show how even without host-unbiasedness, switching is always the right thing to do. I would add some remarks about the unconditional simple solution of Monty Hall himself. This solution follows the point of view of the host that the location of the car is fixed and his choice will be his choice, also fixed, if he has a choice. The player's initial choice is random and hits the car with probability 1/3. He wins the car by switching if and only if his initial choice misses the car (probability 2/3).

My aim throughout would be to minimize computations and algebra, but to maximize ideas, to do justice to the diversity of points of view taken in the reliable sources, and to emphasize the close relations between all the different solutions. Richard Gill (talk) 07:19, 7 January 2011 (UTC)

Really important ideas are: mathematical symmetry; the law of total probability; conditional probability; updating probabilistic information by Bayes' rule in the odds form.

I'd also like to see a small section on the relation between probability interpretations and the consequent meaning (interpretation) of the distributional assumptions and hence the meaning of the probability conclusions. Richard Gill (talk) 16:22, 7 January 2011 (UTC)

Let us not forget there is also an incorrect simple solution, or equivalently combined doors solution. I definitely want these forms of pseudo solutions to be criticized. Nijdam (talk) 17:40, 7 January 2011 (UTC)

You made that claim earlier, but offered no specific support for it, neither your own, or from a reliable source. Glkanter (talk) 18:49, 7 January 2011 (UTC)

I too would like to know which solution you refer to, @Nijdam. One in the present page? Attributed to which source? Richard Gill (talk) 20:27, 7 January 2011 (UTC)

Yes, look in the article. Take for instance Devlin's "solution", or the combined doors solution, which is also shown in a picture. Nijdam (talk) 21:54, 7 January 2011 (UTC)

And Richard, I really am fed up by having to repeat this over and over, without getting an answer. So once and for all, answer to the following, and restrain yourself to what I say. One form of the simple solution reads: Due to the random placement the car is with probability 1/3 behind the chosen door 1. As the opened door 3 shows a goat, this door has clearly probability 0 to hide the car. Hence the remaining door 2 must have probability 2/3 on the car. it is this formulation I'm fighting. Especially because it looks quite plausible and is copied by lots of school pupils and students who gets assignments about the popular MHP. Now just comment on what I wrote here. Nijdam (talk) 22:06, 7 January 2011 (UTC)

@Nijdam, you are absolutely right. "Hence" is wrong. What is said is a nonsequitur. The fact of specifically Door 3 being opened could change the likelihood that the car was originally hidden behind Door 1. So far we only used "all doors initially equally likely" and that isn't enough to get a conditional result, while this argument is about a conditional result, since it talks about how probabilities change (or don't change) on getting the "Door 3" information. There is a missing step where "no host bias" has to be explicitly used. Eg, appeal to independence: by symmetry, the number of the door opened doesn't change the probability the car is behind door 1. Or if you prefer, use Bayes' rule and show by explicit computation that the odds on Door 1 hiding the car isn't changed by the information *which* specific door is opened.

Next task, find a reliable source which explicitly makes this point, because I'm afraid that some editors could consider this observation of yours "OR". (Or write it yourself: why not submit a small note to Statistica Neerlandica?) Richard Gill (talk) 07:24, 8 January 2011 (UTC)

Morgan's misquotation

You guys are worse than Morgan, et al. They faulted the simple solutions because Whitaker/vos Savant didn't make explicit the 50/50 host premise. For a puzzle about a game show. Of course, Morgan says in their rejoinder that maybe only math professors would ever consider that it's not 50/50. Then they finally admit, 20 years later, that it's always 2/3. You guys take it a step further, and criticize the simple solutions for not explicitly repeating that premise as part of the solution. That is the very definition of pedantic. And this is of no benefit to the Wikipedia reader. Glkanter (talk) 10:07, 8 January 2011 (UTC)

Of course, Morgan had to dishonestly modify Whitaker/vos Savant's problem statement in order to make their argument, even though Morgan used quotation marks, from:

"...and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat."

to

"...and the host, who knows what's behind them, opens No. 3, which has a goat."

Maybe the exposure of this canard contributed to their revised, 'it's 2/3, period' 20 years later. You fellas have no such crutch. Glkanter (talk) 10:49, 8 January 2011 (UTC)

Here's Morgan's full misquote of Whitaker/vos Savant:

""Suppose you're on a game show and given a choice of three doors. Behind one is a car; behind the others are goats. You pick door No. 1, and the host, who knows what's behind them, opens No. 3, which has a goat. He then asks if you want to pick No. 2. Should you switch?""

That's barely coherent: "You pick door No. 1, and the host, who knows what's behind them, opens No. 3, which has a goat." What's 'them'? It's an idiotic, poorly conceived word substitution made solely to support their criticisms. Which they, 20 years later, in some continually vague fashion, backed up on. But here we are, still slogging through this nonsense. Glkanter (talk) 11:13, 8 January 2011 (UTC)

I have never noticed that before. This misquotation by Morgan et al has no justification. Martin Hogbin (talk) 11:30, 8 January 2011 (UTC)

They write bad English but it is coherent. "them" refers to the doorS. The host knows what's behind every one of the three doors. Their falsification lies in changing vos Savants parenthetical "say, Door 1", and "say, Door 3" into very definite Door 1 and Door 3. You could delete "say, door 1" and "say, door 3" from vos Savant's words and what would be left would be a completely coherent question which would be perfectly legitimately answered by a (correctly argued) unconditional (i.e, simple) probability solution.

And as vos Savant said later, that was also her semantic intention. Richard Gill (talk) 12:00, 8 January 2011 (UTC)

vos Savant's solutions by the way do not make any use of the 50/50 host choice assumption since they are only aimed at the unconditional probability, for which it this assumption is irrelevant. How many times do I have to remind you of this? Richard Gill (talk) 20:11, 9 January 2011 (UTC)

I disagree with your inference that the simple solutions are an average of all games played only. The indifference by the contestant as to which door has been opened in each single play of the game relies on the doors being equally likely to be opened. If the 50/50 host is required for that indifference, then vos Savant makes use of it. How many times do I have to remind you of this? Glkanter (talk) 20:31, 9 January 2011 (UTC)

Yes, you miss the entire point, Richard, which is that Morgan needed to misquote Whitaker/vos Savant to make their tenuous argument. That you offer your own misquote is actually quite amusing, pointless, and predictable. Glkanter (talk) 12:54, 8 January 2011 (UTC

Yes, the misquotation is important for Morgan's argument. Martin Hogbin (talk) 13:32, 8 January 2011 (UTC)

I have always recognized that Morgan et al deliberately misquote Vos Savant in order to boost their claim that her answer is wrong. Richard Gill (talk) 13:48, 8 January 2011 (UTC)

Devlin and combining doors

Nijdam, would you agree that the only things lacking in Devlin's solution are a statement that the probability of the car being behind the originally chosen door is independent of the door opened by the host and an explanation of why this is so? Martin Hogbin (talk) 11:06, 8 January 2011 (UTC)

Your way of putting this question seems to say: It is not a big mistake Devlin makes, it just needs some extra explanation. No, no,no, Devlin is flat wrong, he's making a serious logical error, he's not to be taken seriously as a source for Wikipedia. His article is just a popular story, not peer reviewed. He makes clear, he does not understand much of probability. I wrote him twice, but no response.Nijdam (talk) 00:04, 9 January 2011 (UTC)

It's hard to tell exactly where he's going with these two new sections on his talk page, but since he needs to include the statement, '...if one were to remove the 'Suppose you're on a game show' premise from the problem statement...' in his comments, he's obviously *not* discussing the MHP. Because there's no Random Monty/Forgetful Host, host bias when faced with 2 goats, or hinting to/telling the contestant where the car is, on a game show. Glkanter (talk) 11:27, 8 January 2011 (UTC)

Both of those two new sections on Nijdam's talk page seem to me to be perfectly clear and reasonable and uncontroversial, I would imagine that any intelligent and MHP-knowledgeable editor could agree with the content. Richard Gill (talk) 12:32, 8 January 2011 (UTC)

I am just trying to establish whether this is Nijdam's sticking point regarding this solution or whether there is another objection to it. I look forward to your response Nijdam. Martin Hogbin (talk) 11:33, 8 January 2011 (UTC)

@Glkanter: not all wikipedia readers use probability in the subjectivist sense. Also if you think "frequentist", and allow for host-bias, you can give a coherent solution to MHP. Your personal limitation in understanding of probability does not imply that only people like you will come to wikipedia MHP for information. And as Nijdam correctly points out, many readers of wikipedia MHP pages are students of probability and statistics and academics in those fields. The pages cannot be limited to a popular approach for the great unwashed, only. Hopefully people who are intelligent enough to edit the MHP pages will be intelligent enough to appreciate, if not to share, other points of view than their own. Fortunately we seem to have made a lot of progress in recent weeks in mutual understanding. Even if you want to focus on the simple solution for the simple people, you still must learn to understand some of the subleties which bother teachers of probability and statistics. It is not just a matter of arrogance or high-priestly-ness that just about all "professional" or specialist writers on MHP seem to prefer conditional solutions. Richard Gill (talk) 12:21, 8 January 2011 (UTC)

I don't know how to "...and allow for host-bias..." while discussing and editing the problem about a game show, where the K & W formulation states the host chooses uniformly at random when faced with 2 goats. Which is the MHP. Which is the subject of the 2/3 & 1/3 vs 50/50 paradox. Glkanter (talk) 12:54, 8 January 2011 (UTC)

And I do know how to allow for unknown host-bias! Neither K&W nor you own a monopoly on the interpretation of Vos Savant's question. Nor on the interpretation of probability. All of which is the MHP-P or meta-MHP. Which indeed includes the subject of the 50:50 versus 2/3 1/3 paradox. Have you read my paper yet? Richard Gill (talk) 13:58, 8 January 2011 (UTC)

BTW Richard, did you notice that K&W forget to mention the assumption that the placement of the car and the player's first choice have to be independent? Nijdam (talk) 00:07, 9 January 2011 (UTC)

No I didn't notice that. Of course everyone does assume that, for good reasons too. Richard Gill (talk) 08:58, 11 January 2011 (UTC)

I will have an interest in your paper only when the Wikipefia MHP article has the NPOV violating simple solution criticisms removed. Otherwise, I remain fat, dumb and happy in my knowledge that the original uniformly at random distribution of the car and goats allows for the proper application of the simple solutions conditioned on the 100% liklihood the host will reveal a goat. Glkanter (talk) 14:41, 8 January 2011 (UTC)

If you want your POV to win in the wikipedia MHP page mediation battles, you need to find reliable sources to support you. One of them is my paper! It says that the simple solution is correct, and it even gives mathematically rigorous (pedantic) support for that. A completely different point, is that the particular argument given by Keith Devlin is faulty or sloppy (or at best: incomplete). Which anybody can see who understands logic and can read English. I can't judge if you are fat and/or happy, but I do think it is dumb not to try to understand the points your fellow editors try to make. Richard Gill (talk) 14:52, 8 January 2011 (UTC)

The NPOV violations exist within the Wikipedia MHP article, not within Glkanter, or his understanding of the MHP or probability. Glkanter (talk) 15:55, 8 January 2011 (UTC)

@Glkanter: it's the job of maths professors to be pedantic. We are merely pointing out that really is a missing step in Devlin's argument. Which in the probability and statistics classroom it is absolutely vital to point out, because in other situations such a missing step could lead to a fatal error, and we want our students to learn correct methods of argumentation and computation; if they get the right answer by a wrong computation that is still wrong. Since Devlin explicitly talks about how some probabilities change when you know specifically that Door 3 has been opened, he ought to ask himself whether or not other probabilities might change too.

@Martin, I cannot speak for Nijdam of course, but in my opinion you are right: the only thing that is missing is the symmetry argument which you just alluded to yourself. The probability of the door being behind the originally chosen door is independent of the specific door opened, by symmetry, under the usual assumptions of no-host-bias or, for subjectivists, prior indifference to host-bias (ie it can equally well be any amount more than 50:50 as any amount less than 50:50. Richard Gill (talk) 11:33, 8 January 2011 (UTC)

If Nijdam would confirm that this is the only basis of his objection to Devlin's solution, we might be able to work towards finding a resolution acceptable to all. Martin Hogbin (talk)

I really do not understand why anyone would be so interested in defending a simple solution, even to the point of deducing the right conditional form from it, as if that would make the simple solution more acceptable. What is it? Does someone have explained in the course of time the MHP with the simple solution, and now in understanding its weakness, desperate tries to find a way out??? I really do not see why someone would otherwise defend the simple solution (the correct form of it of course), except the nitwits of course. Nijdam (talk) 00:17, 9 January 2011 (UTC)

You are entitled to your opinion Nijdam, but that is all it is. I recognise that there is a degree of incompleteness or lack of rigour in the simple solutions but this can, if it is considered really necessary, be corrected by additional wording. Your objection to using the simple solutions with additional clarification or explanation does not reflect any mathematical principle just your personal opinion on the subject. Martin Hogbin (talk) 10:57, 9 January 2011 (UTC)

Martin, you persist in ignoring the point that is being made here. There exist correct computations of the unconditional probability. There exist correct computations of the conditional probability. Devlin's is neither. There is a missing step (and it requires an as yet by him unstated assumption) to make. The probability Door 3 hides a car collapses to 0 when that door is opened revealing a goat. Devlin seems to think that opening Door 3 doesn't tell us anything about whether Door 1 hides a car. But in principle it could do. He fails to provide the argument (and the assumption which is needed to carry through the argument). It is sloppy, unforgiveable.

But anyway, this doesn't matter at all. The wikipedia MHP page doesn't have to reproduce wrong solutions alongside good ones! Devlin's work by the way is just a little opinion-piece, it is not a peer-reviewed academic publication. If any mathematician worth their salt had reviewed it in advance of publication, they would have pointed out the gap in the argument to him. Richard Gill (talk) 20:08, 9 January 2011 (UTC)

I am not ignoring the point, neithet do I not understand it; I do not agree with it. There is no such thing as a 'correct computation', there are computations of varying degrees of rigour. Devlin's solutions give the correct answer to any reasonable interpretation of the problem, including conditional ones. It misses out a step which you may consider necessary but which others may consider obvious. It is therefore less rigorous than some other solutions may be, but the so called conditional solution given in the article is not particularly rigorous either, it does not show the other doors that the player might have chosen. So yes, maybe the conditional solution given is a little more rigorous than Devlin's solution but not much, and what it lacks in rigour it makes up for in ease of understanding and power to convince.

I've now noticed the second Devlin "paper", pointed out by Rick Block. So Devlin himself agreed that his argument was wrong! Of course it is very easy to fix his argument (by symmetry, or by explicit calculation of the Bayes factor, 0.5/0.5=1. But note: either way, it is an argument for the Conditional solution! That's the important thing to recognize! Richard Gill (talk) 08:58, 11 January 2011 (UTC)

You say, 'Devlin seems to think that opening Door 3 doesn't tell us anything about whether Door 1 hides a car. But in principle it could do'. According to what principle? Only the principle that to answer a different question we require a different method of solution. Martin Hogbin (talk) 23:56, 9 January 2011 (UTC)

No @Martin, this is according to the principle that if you condition on a non-certain event, any probability can change. And some probabilities certainly do change. As Devlin correctly deduced. The "principle" in question is the universal law P1(A|B)=P1(A&B)/P1(B), where, for us at the moment, "P1" refers to probabilities given that the player chose Door 1, A is the event "Car is behind Door 1", and B is the event "Host opened Door 3". Devlin correctly notes that with regards to the event C "Car behind Door 3", P1(C)=1/3 but P1(C|B)=0. So he sure is using conditional probability! And he sure has missed a step of the argument. That's all. Whether or not you and most wikipedia readers are satisfied with intuitively appealing but logically faulty arguments is quite irrelevant.

Just because one author screws up, doesn't mean that every author's presentation is a mess. Gill (2011) and Sevlin both present both simple and conditional solutions, both correctly. Devlin tries to do the conditional solution but does it wrong. Better not to confuse wikipedia readers by presenting faulty arguments. Of course new editors will then come along and remove or correct them. Richard Gill (talk) 09:07, 10 January 2011 (UTC)

@Glkanter: please distinguish between a) what we want to calculate, and b) whether or not our method of calculating it is correct. Quite a few lovers of simple solutions are interested in an unconditional probability and give a correct computation of an unconditional probability. Nijdam himself has the point of view that we should not be interested in the unconditional probability (and he has a good reason for this), but still, that is just an opinion. Devlin seems to have the same opinion. Devlin explicitly conditions on specifically Door 3 revealing a goat. Right now we are not discussing conditional versus unconditional, but talking about something else: the correctness of a specific source's probabilistic reasoning. Devlin's *reasoning* is just  !$#*-ing wrong, or if you would like to be more polite, incomplete. It is not a simple (unconditional) solution. It's a screwed up conditional solution. Richard Gill (talk) 14:04, 8 January 2011 (UTC)

I've just emailed to Keith Devlin about his really shocking mistake / missing proof step. He may be a mathematician but he's a bad probabilist and a dangerous science popularizer if he makes blunders like that. His response will be interesting. Richard Gill (talk) 13:52, 8 January 2011 (UTC)

You might be interested in Devlin's December 05 column, see [20]. -- Rick Block (talk) 18:03, 8 January 2011 (UTC)

This seems to be standard stuff, 2/3 if the host knows where the car is, 1/2 if he does not. Have I missed something? Martin Hogbin (talk) 18:12, 8 January 2011 (UTC)

You do miss it all. Nijdam (talk) 00:19, 9 January 2011 (UTC)

Perhaps you could be more specific. Martin Hogbin (talk) 10:57, 9 January 2011 (UTC)

Devlin is showing that the simple explanation is "correct" only under assumptions that it does not explicitly use - since the same "correct" explanation seems to apply but leads to the wrong result for what is effectively the "host forgets" variant. He then goes on to say "As sometimes arises in mathematics, when you find yourself in a confusing situation, it may be easier to find the relevant mathematical formula and simply plug in the appropriate values without worrying what it all means." - i.e. if you want to know the conditional probability then use Bayes rule to figure it out rather than some "intuitive" explanation that might or might not apply. -- Rick Block (talk) 22:26, 8 January 2011 (UTC)

Rick, so you really believe in "Host forgets" and D.? I don't, and no more in the Flat Earth. And I hope this is not my mistake. Gerhardvalentin (talk) 00:52, 9 January 2011 (UTC)

That criticism/explanation, while not original, does not seem to hold up to the standards of scientific (formal?) logic, in terms of disqualifying the solution as invalid. In other words, it's bogus. 22:36, 8 January 2011 (UTC) — Preceding unsigned comment added by Glkanter (talk • contribs) 22:37, 8 January 2011 (CEST) (UTC)

Exactly as I said, the answer is 2/3 if we adopt the universally accepted standard rule that the host knows where the car is and 1/2 for what he calls 'a slightly modified version of the Monty Hall game' in which the host does not know where the car is. We all know this. I cannot see any relevance to the current discussion. Martin Hogbin (talk) 22:33, 8 January 2011 (UTC)

No Martin. The *conditional* answer is 2/3 if we adopt ... AND if we assume no host-bias (or if we are subjectivists, indifference to the direction of host-bias). Devlin gives the answer 2/3. His derivation is clearly conditional, he talks about specifically Door 3 being opened and how the probability the car is there then drops to 0. He silently assumes the probability the car is behind Door 1 doesn't change on being given this information. He does not explain how it is that he knows that opening Door 3 doesn't change is odds on Door 1 hiding the car. So to put it charitably, he was a bit quick and skipped a step. He not only skipped a step of the argument, he also skipped mentioning the assumption which he was using to make this step. Pretty shoddy stuff for someone who calls themselves a mathematician! I have written to him about this.

The answer is always 2/3 for the standard rules provided only that we are consistent in our approach (apart from the trivial case that the problem is insoluble). See section below.

I thought that Rick was suggesting that there was something new in Devlin's Dec 05 column compared with his 2003 comments. I was just pointing out that there is not. Devlin says much the same in both articles.

Devlin does not say how we know that the probability of the car being behind door 1 does not change when the host opens door 3. This is an omission but how important it is is a matter of opinion. Some may consider the fact obvious. Martin Hogbin (talk) 19:22, 9 January 2011 (UTC)

This is not to say that every simple solution is wrong. It is legitimate, in my opinion (and in the opinion of many authorities, eg vos Savant, Selvin, ...) to be interested in the unconditional probability that switching gives the car. And there exist correct arguments that that probability is 2/3. One of the correct arguments is that the host is essentially offering you the choice between Door 1 and Door 2 + Door 3. I have written up a completely respectable formal mathematical version of that argument, many many times. Richard Gill (talk) 15:43, 9 January 2011 (UTC)

Yes, I think we all agree that the simple solutions are correct for the unconditional case, the question is, how wrong are they for the conditional case? In my opinion, not very. Martin Hogbin (talk) 19:22, 9 January 2011 (UTC)

Mathematical puzzles ought to be solved by correct mathematical arguments. There are correct derivations of the unconditional probability that the switcher wins. There are correct derivations of the conditional probability that the switcher wins, given a specific door chosen and door opened. There is no point in wasting wikipedia space with nonsense (derivations which are just plain wrong, i.e., illogical). Devlin's argument is faulty but fortunately there is absolutely no need to report it on the wikipedia MHP page. There are plenty of "correct" simple solutions out there. Monty Hall, Selvin, Gill (2011), vos Savant... Richard Gill (talk) 19:54, 9 January 2011 (UTC)

It's clearly a matter or opinion how MHP should be translated into a formal mathematical problem: what assumptions should be made, and what constitutes a solution (what is the target object to be computed). Given a particular assumption-set and particular target there exist correct solutions and incorrect solutions. Devlin's solution is incorrect. He skips an important step in his chain of reasoning. There is no way to tell if he was aware of it or not. Richard Gill (talk) 20:01, 9 January 2011 (UTC)

Lemme make sure I have this straight: Devlin's valid solution gets thrown in the scrap heap because you guys have decided his presentation has an omission, but Morgan's paper remains the 800 lb. gorilla of simple solution criticism despite countless errors, including the one Martin & Nijdam made them admit, the dishonestly changed Whitaker/vos Savant quote, and all the rest of them as Martin has cataloged? You guys crack me up. But there's nothing funny about it. Glkanter (talk) 20:09, 9 January 2011 (UTC)

Devlin's argument misses a crucial step. Can't you see that? So what is the point of refering to it on the wikipedia MHP page? Wouldn't it be a service to the reader just to concentrate on the sources who give logically sound arguments for whatever they think is the right kind of solution to the problem? Both simple and conditional?

As for Morgan et al's paper, I am not aware of anyone who wants to make it some kind of centre-piece of the page. Personally I think it is a bad paper. It falsifies history so as to boost their own interpretation of the problem; the mathematics is opaque and clumsy; and it does not explain why a conditional solution should in any way be seen as better than an unconditional solution. Fortunately there are sources which do the conditional solution (with or without host-bias) in a much more simple and transparent way, and there are sources which explain what is the "bonus" of a conditional solution. There are also sources which explain the down-side --- in order to get more detailed conclusions, you need to make more detailed assumptions, and that limits the scope of your solution. Richard Gill (talk) 20:22, 9 January 2011 (UTC)

Oh, please. "Morgan is (are?) God(s)" should be the banner for the 'simple is flawed' arguers. No other reliable source says they are 'false'. Equating Devlin's presumption of the obvious to Morgan's intentional and careless errors is just silly. And there is no 'bonus' available by doing the conditional solution to the MHP. I have shown countless methods of proving that 'switch' is always the best decision, in every single play of the game. "How many times do I have to remind you of this?" Glkanter (talk)

Richard, Devlin's argument misses a step that you consider necessary but which others may consider not to be needed. To most people it is intuitively obvious that the number of the door that the host opens cannot affect the probability that the car is behind door 1. This turns out to be correct for any reasonable and consistent set of assumptions. Martin Hogbin (talk) 20:44, 9 January 2011 (UTC)

Martin, lastly it's the old argument of extreme host's bias again, in another variant, giving additional info on the actual location of the car: Because of door#3 can be hiding a goat (to be shown) only in 2 out of 3, and in exactly those 2 out of 3 the door#1, originally selected by the guest, either (1/2) hides the car or (1/2) the other goat, so in opening of "door 3" Pws is said to be 1/2 only. Cit.: "And it even gives mathematically rigorous (pedantic) support for that."   Gerhardvalentin (talk) 21:23, 9 January 2011 (UTC)

Yes, I know what it is all about, but there is no reasonable set of assumptions that gives an answer other than 2/3, even Morgan agree this now. Martin Hogbin (talk) 22:34, 9 January 2011 (UTC)

@Martin: Devlin (who claims to be a mathematician) carelessly omitted a small and simple but logically absolutely necessary step in his little chain of arguments. Whether or not you or @Glkanter or Mr and Mrs Average would lose any sleep on this, is totally beside the point. Devlin's argument, with its missing step put correctly in its correct place, is an argument for the conditional solution. That's The Truth!

Which steps in any given calculation are absolutely necessary and which are not is a matter of opinion. I believe that the step that Devlin omitted is obvious and therefore not absolutely necessary to include. Martin Hogbin (talk) 15:45, 10 January 2011 (UTC)

The missing step is not obvious, and it requires an appreciation of the difference between a conditional and an unconditional probability. Devlin admits himself that it's important (thanks @Rick Block). Devlin is doing the conditional solution and he does it wrong, full stop. Richard Gill (talk) 08:58, 11 January 2011 (UTC)

I think the wikipedia MHP editors would be wise to take account of this by some minor editing. That way they will end up presenting the full conditional solution in a completely transparent and intuitively delightful way, thereby totally taking the wind out of the sails of all those annoying people who want to go on a crusade about the enormous difference between the two kinds of solutions. Richard Gill (talk) 08:51, 10 January 2011 (UTC)

Here I agree with you. I have proposed that we do some minor editing and was trying to negotiate something with Nijdam. However, as you said, most people will not be interested in this rather pedantic point so we should be careful not to compromise clarity for the majority in the cause of pedantry for the few. I stress that this is only for the 'Simple solutions' section. After that we can go into the subject in as much detail as necessary to give a full and accurate understanding. Martin Hogbin (talk) 15:45, 10 January 2011 (UTC)

Martin, it would help us all if you would only open your eyes! Devlin has introduced a 3rd party to the MHP, in the form of a 2nd contestant. It is only in this way that the Random/Forgetful host of a game show denying the contestant the opportunity to win the car makes sense. And as another editor pointed out today, Selvin does not 'own' the MHP. So, this new 3 player, reduced sample space problem is *also* the MHP! Selvin naming the problem the MHP, stating the host will always reveal a goat, has no bias between goats, giving a simple solution only in his first letter, and profusely praising Monty Hall's simple solution are obviously besides the point. Wake up and smell the coffee, Martin! Glkanter (talk) 22:51, 9 January 2011 (UTC)

Selvin profusely praised Monty Hall's simple solution in his second letter, after doing the full conditional solution, in contrast to his first letter. Monty Hall's simple solution does not make any host-side assumptions at all, but takes the host-side point of view that it is the player's initial choice which is completely random. Selvin's two letters contain both simple and conditional arguments, with just about all possible combinations of answers. In fact his paper is similar to Gill (2011) in that he offers the reader a spectrum of decent mathematical formulations of the problem and decent solutions thereof, each with their own strengths and weaknesses. Richard Gill (talk) 08:51, 10 January 2011 (UTC)

Devlin and not combining doors

@Rick Block is of course completely right: in Devlin's second internet posting (neither of these items can be called "papers") he has noticed that his original argument was faulty. Moreover he explicitly admits that he was after the conditional solution, too. There is however an alternative to "going back to first principles and doing it the hard way with Bayes' formula". We here know two "quick fixes" to Devlin's short argument.

Fix 1: symmetry. The conditional probability that the car is behind Door 1 given the player chose 1 and the host opened Door 2 is equal to the conditional probability that the car is behind Door 1 given the player chose 1 and the host opened Door 3, by symmetry (since we take the full K&W conditions on board). Therefore, given the player chose Door 1, whether or not the car is behind Door 1 is independent of whether the host opened Door 2 or Door 3. And that means that the probability the car is behind Door 1 given the player chose 1 and the host opened 3 equals the probability the car is behind Door 1 given only that the player chose 1, and we already know that that equals 2/3.

Fix 2: Bayes rule, odds form. The odds on the car being behind Door 1 given the player chose Door 1 are 1:2 against. If the car is behind Door 1 (the door chosen by the player) the probability the host opens Door 3 is 0.5 (no host-bias). If on the other hand the car is not behind Door 1 (the door chosen by the player) the probability the host opens Door 3 is 0.50, because the car is now equally likely behind Doors 2 and 3, and he is forced to choose the other one. The Bayes' factor or likelihood ratio is therefore 0.5/0.5 = 1, and the posterior odds remain at 1:2 against.

Both fixes to Devlin's argument are easy, but both are subtle, neither is completely obvious. They are especially not obvious to people who are not familiar and comfortable with the difference between conditional and unconditional probabilities. Precisely such persons will on the other hand not even notice the missing step, let alone come up on their own with a rigorous argument which fills in the gap.

We should put both corrected versions of Devlin's argument into the conditional solutions section, where they belong.

On the other hand, Devlin's remark about the host offering you the choice between Door 1 and Doors 2 + 3 is spot on: it's a perfect short simple solution to the problem of determining the unconditional probability. Richard Gill (talk) 09:28, 11 January 2011 (UTC)

So, contrary to Nijdam's recent proposition that the Combined Doors simple solution is flat out wrong, you've determined that:

It is correct

It is conditional

Devlin's logic also supports a perfect simple solution

I'm pretty much OK with the above. I've argued with Rick in the past that the Combined doors solution is clearly after door 3 has been revealed. I think this was when he first trotted out his Solution section re-write that omitted it, about July-ish. Glkanter (talk) 11:10, 11 January 2011 (UTC)

No @Glkanter, my opinion is that a combined doors simple solution is correct and unconditional ("the host is offering you the choice between Door 1, and Door 2+3: therefore the unconditional probability that switching gives the car is 2/3"). Devlin's solution is a botched conditional solution, as he realised himself in his second writing. Richard Gill (talk) 17:14, 11 January 2011 (UTC)

Richard, you say 'They are especially not obvious to people who are not familiar and comfortable with the difference between conditional and unconditional probabilities. Precisely such persons will on the other hand not even notice the missing step, let alone come up on their own with a rigorous argument which fills in the gap'. This is pretty much what I have been saying all along. After the vos Savant's solution it was around a decade before anybody, including statisticians and mathematicians noticed the potential conditional aspect of the MHP (although Selvin had addressed this aspect originally).

The really amazing thing about the MHP is that people resolutely believe the answer is 1/2. There is no evidence to suggestion that this as has anything whatever to do with whether the problem is conditional or not. As you quite rightly say, nearly everyone does not even notice the difference. Also, I believe that the symmetry with respect to door number would be obvious to most people if they were asked, for example, on being asked 'Would it have made any difference to your answer if the host had revealed a goat behind door 2 rather than door 3?', I am sure most people would reply, 'Of course not!', but I guess this is OR. Obviousness is an interesting topic in mathematics, I am sure you know the well known story on the subject.

So, Richard, why not give the simple solutions first, without complication, because there are many justifications for doing this, and then, for the small pedantic minority, discuss the more complex issues in proper detail? Martin Hogbin (talk) 12:16, 11 January 2011 (UTC)

@Martin: yes, I do recommend you MHP page editors give the simple solutions first without complication! I am saying that Devlin's pseudo-mathematical solution is a botched conditional solution, so it would be wise to leave it out entirely. Do include the "Door 1 versus Doors 2+3" simple solution. Why can't we *all* have our cakes and *all* eat them too? Present first sound simple arguments for the unconditional solution, and after that build on them to present sound and hardly more complicated arguments for the conditional solution, in particular, using both of the fixes which I wrote out to Devlin's argument. That way we are both respecting The Truth and the needs of two kinds of readers. Richard Gill (talk) 17:14, 11 January 2011 (UTC)

Martin - your claim that "There is no evidence to suggest that this as has anything whatever to do with whether the problem is conditional or not." is simply wrong. According to Krauss and Wang, fully 97% of their test subjects drew a picture where door 3 is open showing a goat. These subjects are clearly trying to solve the conditional problem where it is given the player has picked door 1 and the host has opened door 3 (not the player has picked door 1 and the host has opened "a door" showing a goat). It is this problem, where the "probability" (the conditional probability) the car is behind door 3 is obviously 0 and the car must be behind one of door 1 or door 2, that nearly all people try to solve. This problem leads to the erroneous 1/2 answer, but 1/2 door 1 and 1/2 door 2 which are conditional probabilities (not 1/2 door 1 and 1/2 "door 2 or door 3, whichever one the host didn't open"). -- Rick Block (talk) 14:24, 11 January 2011 (UTC)

Is that after hearing a problem where 'another door, say #3' was opened to reveal a goat? So what? 97% of the people tested have good hearing. How about vos Savant saying in over 10,000 letters, it never came up? Glkanter (talk) 15:41, 11 January 2011 (UTC)

I, and many others, always figured it was 'the car is either behind the door I chose, or the other one remaining'. Same condition, with indifference. Glkanter (talk) 15:45, 11 January 2011 (UTC)

No, @Glkanter. Suppose you've chosen Door 1. Then there is actually a subtle difference between knowing that another door is opened revealing a goat and you have the option of switching to the third, and knowing that Door 3 is opened revealing a goat and you have the option of switching to Door 2. Vos Savant intended (she has said so, and this also corresponds to her solutions) that you could delete the words "say, Door 3" - this is a parenthetical remark to make things clear for you: the door opened would have to be Door 2 or Door 3 if your own choice was Door 1. You were also intended also to delete the words "say, Door 1".

vos Savant's intention was *not* that you should think about the situation *after* Door 1 is chosen and Door 3 is opened. However as Kraus and Wang point out, most people do create this picture in their minds, and indeed, that is one of the roots of the error which most people make. What you see in this picture is namely only a part of the information you learnt. You also got information in the way those doors got to be opened or closed.

If you are a player with a problem with short term memory and you choose your door initially at random, then step aside, then Monty opens a/the goat door, and steps aside, and you forget who did what, then all you see are two closed doors and one open. The chance truly is 50/50 given only this information, which door hides the car! The "wrong" intuitive solution is actually completely correct for a super-forgetful player who only sees what is in front of him, and who must decide at a moment when both he and the host have moved away from their chosen doors. Richard Gill (talk) 17:14, 11 January 2011 (UTC)

It's too bad you cannot perceive your own writings the way they come off to others. You reached a new level of absurdity with the above paragraph. Kudos, Richard. I didn't think it possible. Glkanter (talk) 17:21, 11 January 2011 (UTC)

2/3 is the answer - What is the question?

It astonishes me that you write "the answer is 2/3". The MHP does not ask for something this could be an answer to. So what does 1/3 answer? During more than 2 years we are discussing, and one point of discussion is exactly what the number 2/3 means, and yet you come up with such an sentence. Nijdam (talk) 10:37, 9 January 2011 (UTC)

Of course on any other forum I would consider it necessary to explain what I mean but here the question of what 2/3 is the answer to is well known. To be more specific, 2/3 is the probability (based on any generally accepted meaning of the term) that the player of the MHP game, with the standard rules, will win by switching in the following cases:

1. The unconditional formulation, that is to say the player picks a door and the host opens another to reveal a goat.
2. The conditional formulation, given that the player picks door 1 and the host opens door 3 to reveal a goat.
3. As 2 with any specified legal door numbers.
4. The host is known to have a door preference but the player has initially picked a door uniformly at random.

Do you dispute any of these? Martin Hogbin (talk) 11:45, 9 January 2011 (UTC)

Birds

Hi Martin. Please note that it is a Bird Project convention that all bird species are fully capped, thanks Jimfbleak - talk to me? 07:06, 1 January 2011 (UTC)

Who am I to argue, but this a new one to me. How widespread (outside WP) is this convention? Martin Hogbin (talk) 11:30, 1 January 2011 (UTC)

Starting points

I urgently ask the participants to respond to Wikipedia talk:Requests for mediation/Monty Hall problem/Starting points. This may show us where we still differ in opinion. Nijdam (talk) 11:03, 9 January 2011 (UTC)

Who can give an example of when "The contestant should not switch in this particular play of the MHP"?

Anyone? Because the misstatement of the simple solutions as (1)'the average of the outcomes of always switching' is still comprised of (2)the aggregate of infinite 'in each single, unique play of the game, switch'. #2 would have to be false for a better strategy to exist. Glkanter (talk) 23:02, 9 January 2011 (UTC)

" 'the average of the outcomes of always switching' is still comprised of the aggregate of infinite 'in each single, unique play of the game, switch' " is gibberish to me. What are you talking about, @Glkanter? Richard Gill (talk) 13:48, 10 January 2011 (UTC)

In fact, who can even give a reasonable example in which the probability of winning by switching is not 2/3 (with the standard rules, as always). Martin Hogbin (talk) 23:58, 9 January 2011 (UTC)

Of course, the whole thing remains pointless. Sadly, as I wrote nearly 2 years ago, it's just a bunch of gibberish. A game show problem about 3 equally likely doors. Why is the solution so complicated, requiring 'new inquiries' into the MHP? Whatever happened to '1/3 <> 1/3', anyways? Glkanter (talk) 04:17, 10 January 2011 (UTC)

Discussion is indeed pointless as long as participants don't recognise the difference between a correct argument and a correct answer. Nobody is disputing 2/3, nobody is disputing that the contestant should switch. Everyone is happy to accept the standard and full collection of familiar premises.

If one imagines many repetitions of the game in which the true location of the car varies completely at random and the initial door chosen by the player varies in any way you like (or not at all), then (A) always switching will give the player the car in 2/3 of the times. Those many repetitions can be separated into up to six subgroups of repetitions according to the initial choice of the player, and the door opened by the player. (I say "up to 6" because if for instance the player always chooses door 1 there will only be 2 subgroups). If the host's choice of door to open is also completely random, when he has one, then also (B) in each of those up to six subgroups of repetitions, a switching player gets the car 2/3 of the times.

Surely both @Martin and @Glkanter can agree that it must cost a little more thought and/or logic to convince a nit-picking sceptic of the truth of the more refined conclusion (B) than of the rather basic conclusion (A).

Right now, no one here is fighting about whether one should solve MHP in the form of a statement like (A) or like (B). Right now, no-one here is disputing the host-side assumptions of completely random car-hiding and door-opening. Right now, all we were doing was discussing a little error in the presentation of one of the sources (Devlin): a source which pretends to give the conditional solution, not a simple solution at all! It is an internet page, an opinion piece by a Big Man. A couple of sound-bytes for his fans. It's not an academic, peer-reviewed publication.

Nijdam has correctly pointed out that the specific argument given by Devlin misses a key step. Devlin silently uses the fact, but does not explain why it is true, that the probablity Door 1 hides the car doesn't change on revealing a goat specifically behind Door 3. That's a real blunder when made by someone who claims to be a mathematician and puts themselves forwards as a popularizer of science. It's clear to me that Devlin is not a probabilist. He hasn't thought MHP through carefully. Devlin tries to give the conditional solution (B) but doesn't give a correct argument for it!

On the other hand, arguments on the lines of "the host is offering you the choice of Door 1 versus Door 2+Door 3, therefore you should switch (2/3 versus 1/3)" are completely correct. The probability Door 1 hides a car doesn't change on revealing a goat behind one of the other doors, as yet unspecified. So it remains 1/3, and the other as yet unspecified door hides the car with probability 2/3. Richard Gill (talk) 08:20, 10 January 2011 (UTC)

I started a new section on Martin's talk page. This has nothing to do with Devlin, obviously. Do you have an answer to the question in this section's title? Or is there no way for some different strategy to improve on the very simple 'switch'? Glkanter (talk) 08:55, 10 January 2011 (UTC)

"Ask a stupid question, get a stupid answer". No I can't give an example. The title of this section is silly. It's a section about a non-topic. . Richard Gill (talk) 09:23, 10 January 2011 (UTC)

All that matters is that you, or anyone, can't describe a scenario where it's better to stay. That means that in every play of the game it's best for the contestant to switch. All that stuff about 'optimal' solutions and 'min/max' is of no incremental value. And, as Martin pointed out, each play of the game is, of course, 2/3 & 1/3. Glkanter (talk) 10:37, 10 January 2011 (UTC)

Of course, it's nice to see you write unambiguously:

"On the other hand, arguments on the lines of "the host is offering you the choice of Door 1 versus Door 2+Door 3, therefore you should switch (2/3 versus 1/3)" are completely correct. The probability Door 1 hides a car doesn't change on revealing a goat behind one of the other doors, as yet unspecified. So it remains 1/3, and the other as yet unspecified door hides the car with probability 2/3. Richard Gill (talk) 08:20, 10 January 2011 (UTC)"

I think you properly described 'indifference', rather than 'before a door is opened'. Of course, that supports Devlin's solution as well. I'm anxious to hear what the other editors think of your statement. Glkanter (talk) 09:03, 10 January 2011 (UTC)

No @Glkanter, I am not talking about indifference, I am talking about before/after. Because Devlin is doing that himself, explicitly. Before Door 3 is opened the probability the car is there is 1/3. Afterwards it is 0. He says so himself. Nothing to do with indifference. He nowhere says anything explicit about his indifference as to whether Door 3 or Door 2 is opened; but he should have done. Because of his indifference (because of symmetry), the probability Door 1 hides a car is independent of whether Door 2 or Door 3 is opened, i.e., the conditional and unconditional probabilties that Door 1 hides a car are the same. See any first course in probability. If B has non-zero probability, then A is independent of B if and only if the conditional probability of A given B equals the unconditional probability of A. Richard Gill (talk) 09:19, 10 January 2011 (UTC)