Talk:F-statistics

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I started a page on Fst without realizing that this page about F-statistic existed. I discovered this one and do not know if I should erase my page or not. However, I go in a different direction and it would take a lot of editing to fit what I want to say into this page. Any recommendation about what I should do?

INCORRECT This is not the correct definition of F. It should be

${\displaystyle F={\frac {\operatorname {E} {(f(\mathbf {Aa} ))}-\operatorname {O} (f(\mathbf {Aa} ))}{\operatorname {E} (f(\mathbf {Aa} ))}}\!}$

I haven't checked the entire article, but the mistake may very well be carried through. I'll check and fix it when I get some time. Ted 22:12, 10 March 2006 (UTC)

Mostly done. I haven't checked the section FST. I don't use that definition. Ted 18:52, 11 March 2006 (UTC)

Error correction: Reduction in heterozygosity rather than homozygosity

I replaced homozygosity with heterozygosity in second part of first sentence:

"more specifically the degree of (usually) a reduction in heterozygosity when compared to Hardy-Weinberg expectation"

Ian.

Aetheogamous (talk) 19:36, 18 June 2008 (UTC)

This formula is not properly stated

A common definition is the following:
${\displaystyle F_{ST}={\frac {\operatorname {var} (p)}{p\,(1-p)}}\!}$
where the variance of p is computed across sub-populations and p(1 −p) is the expected frequency of heterozygotes.

Obviously that doesn't make sense; it seems the thing in the numerator was supposed to be the bold-face p rather than p. I changed it to this:

A common definition is the following:
${\displaystyle F_{ST}={\frac {\operatorname {var} (\mathbf {p} )}{p\,(1-p)}}\!}$
where the variance of p is computed across sub-populations and p(1 −p) is the expected frequency of heterozygotes.

But it doesn't say what the random variable called (bold-face) p actually is. Anyone not offended by this isn't paying attention. Michael Hardy (talk) 18:01, 11 October 2009 (UTC)

Lay persons

I have a double A-level in maths, but I have no idea what "obs" means in an equation. Any chance of a lay person's version? As far as I know about genetic statistics, all I know is that if I leave my playstation on overnight, I'm helping people who understand this shit.

obs means "observed", used in population genetics when comparing expected and observed values Jebus989 09:31, 5 May 2011 (UTC)

Incorrect information for the F example used.

Under the section Definitions and Equations, where an example is given of how to calculate ƒ(AA) for the population, I believe the equation given is actually for ƒ(Aa). I'm not an expert on the topic so I don't dare change it myself but I have marked it as dubious. -biocrite {📠Talk📝Contribs} 13:37, 27 February 2015 (UTC)

Fixation index in human populations

This section strikes me as being irreparably flawed:

"It is well established that the genetic diversity among human populations is low,[3] although the distribution of the genetic diversity was only roughly estimated. Early studies argued that 85–90% of the genetic variation is found within individuals residing in the same populations within continents (intra-continental populations) and only an additional 10–15% is found between populations of different continents (continental populations).[4][5][6][7][8] Later studies based on hundreds of thousands single-nucleotide polymorphism (SNPs) suggested that the genetic diversity between continental populations is even smaller and accounts for 3 to 7%[9][10][11][12][13][14] Most of these studies have used the FST statistics [15] or closely related statistics.[16][17]"

Regarding the first sentence, in population genetics, the following standards are often employed:

0 to 0.05 indicates little genetic differentiation 0.05 to 0.15 indicates moderate genetic differentiation 0.15 to 0.25 indicates great genetic differentiation 0.25 indicate very great genetic differentiation

Sewall Wright (1978); Hartl and Clark (1997): Oliveira et al. (2007); Zhang and Tier (2009).

Genetic differentiation obviously depends on the populations in question and the markers used. For continental human populations, the SNP Fst value (K=3 to 5) is said to be around 0.12 (Li et al., 2008; Elhaik, 2012; Bhatia et al., 2013; Campbell and Tishkoff, 2008). The microsatellite Fst values are typically around 0.05 and the haploid e.g., MtDNA values are around 0.20. I am not sure how you get low out of moderate, except by citing someone who idiosyncratically interprets the Fst values accordingly.

The last sentence is false and is contradicted by the wiki page on fixation indexes: https://en.wikipedia.org/wiki/Fixation_index I would advise just deleting the paragraph until the primary author can correct the errors. — Preceding unsigned comment added by Zebrapersonfrank (talkcontribs) 21:30, 14 May 2015 (UTC)

No.

As I noted above, the passage in this section contains errors. Until these are fixed the section needs to be removed. The first statement makes little sense because the apportion of genetic diversity among human populations depends on the populations in question. Let's try the following sensible rewrite:

"It is well established that the genetic diversity among continental human populations is moderate to low. Studies indicate that between 85–95% of the genetic variation is found within continental populations."

(never mind, the other stuff is mentioned.) --Zebrapersonfrank (talk) 06:22, 24 May 2015 (UTC)