Wikipedia:How to mine a source
This page is a how-to guide detailing a practice or process on the English Wikipedia.
|This page in a nutshell: Sources are rarely plundered for all they are worth, and articles with "citation needed" tags often already have sufficient sources that simply have been under-utilized. Most new sources added for a detail or two can also be dug into for additional sourcing value.|
It is very common for Wikipedia editors to add a citation, such as to a newspaper or magazine article, a book chapter, or other hopefully reliable publication, to source the verifiability of a single fact in an article. Most often the editor has found this source via a search engine, or perhaps even a library visit, seeking a source for a detail in an article, some pesky tidbit without a citation. This common approach, akin to stopping at the grocery store for eggs and milk and nothing else, rather than "working" the store for an hour with a long shopping list and an eye for bargains, tends to miss many opportunities to improve both the content and the sourcing of articles.
This tutorial offers a very short, but real-world example of how to "mine" a source, and really work it like a seam of ore for every last bit of verifiability gold. In addition to noticing facts in your source that are missing from the article, and noticing that your source can also provide a citation for more facts already in the article than the one(s) you were most concerned about, you can also often double-up citations on a fact that already has one source cited. While the average fact in an article does not need seven citations, two rarely hurts, and can provide a cushion if something is found faulty with the other source and it is deemed unreliable, or a third, questionable, source challenges the first.
 Example article
The article Manx (cat), on the domestic cat breed, like most cat (and dog, and horse, and orchid, etc.) variety articles needed a lot of work as of late 2011. In particular, even though it linked to many current breed standards, it was missing information on the early history of the variety. Google Books actually turns out to be very useful for old "natural or traditional breeds" like the Manx, because it tends to have the full text of sources that are no longer covered by copyright. One such source was Charles Henry Lane's Rabbits, Cats and Cavies: Descriptive Sketches of All Recognized Exhibition Varieties (1903) with a detailed if short chapter on the Manx. This piece was "mined" first, and the Wikipedia article vastly improved with it, but this was too rich and complex an example to make a good case study.
 Example source
A better example for this page's purpose was found a bit later. It is a much shorter chapter, from The Cat: Its Points and Management in Health and Disease by Frank Townend Barton (1908). Since it is out of copyright, and quite short, we can just quote the full text of his "The Manx Cat" here:
The Manx cat—the origin of which is involved in obscurity—chiefly exists in the Isle of Man, and has been found also in the Crimea and Cornwall. Few specimens are now found.
The suppression of the tail constitutes one of the characteristic features of the breed. Manx cats by no means breed true to type, any more than the bob-tailed sheep-dog or schipperke does, and if the aborted caudal appendage is removed, it makes the cat quite as good as though it had been born with a total absence of tail. It is the absence of tail that gives the peculiar appearance to the Manx Cat, being akin to that of the rabbit in the hinder part, owing to the length of the limbs.
With reference to colour of coat, the Manx may be of any colour, but probably black is most frequently met with.
There is nothing whatever to recommend the breed, whilst the loss of the tail in no way enhances its beauty.
If a short tail is present, it should be removed whilst the kitten is a few days old, and there is no doubt that many spurious Manx cats exist, as the result of this simple operation, practised for deception.
Yep, that's the entire chapter. At first glance, it hardly seems worth bothering with.
Attention was first drawn to this chapter because of its mention of similar cats in Cornwall and Crimea, details other sources so far had not discussed. But there is actually a quite large number of facts (i.e., in Wikipedia terms, nontrivial statements of fact from an independent, non-fringe, apparently reliable, professionally published work) to be dug like gems from this source.
 Example of mining this source for all it's worth
It is tempting to simply skim this source and edit the article for a point or two and move on, but it's quite easy to miss something (indeed, the fact that Manx cats were thought of by Barton as scarce and possibly even declining was missed until preparation of this essay). It is best to make a list of facts (e.g. in a sandbox page or a text editor), in wiki markup and in sentence or easily usable sentence fragment form, and already carefully rewriting to avoid plagiarism. Start with the first sentence and work your way down. It might look something like this, including notes based on sources already cited in the article:
- The Manx's ultimate origin is unknown. [It was as of 1908, and still is now according to other sources, but genetic study could change that at any time.]
- Most specimens were then found on the Isle of Man. [This was long before the world-wide explosion of cat breeding.]
- Similar cats were also found in Cornwall and Crimea. [That they are exactly the same as Manx cats as Barton seems to suggest is not credible from a modern, post-genetics perspective; i.e. on that point of heredity, Barton cannot be a reliable source.]
- We know from the Japanese Bobtail and Kuril Islands Bobtail that stunted-tail cats are a common type of mutation in insular, isolated populations but not necessarily the same mutation.
- But we also know from other sources that Manx cats were popular as ship's cats, so they could have simply spread to Crimea by ship. [Needs more sources. We can't draw any conclusions yet; that would be original research.] Other sources also mention them in Denmark, etc. [This is all interesting enough to mention without advancing a theory.]
- Cornwall is not very far from the Isle of Man. [Again, we can't put words in the source's mouth, but simply noting this is enough to let the reader think about it; one of them might even find some evidence we're lacking that Manx cats originally came from Cornwall, or Cornish tailless cats originally came from the IoM.]
- As of 1908, the breed was uncommon. Barton implies clearly that they are declining. [It's tempting to say "even on the IoM", but honestly the original passage is a bit vague, and an inference that specific would be another form of OR.]
- One of the defining characteristics of the breed is "suppression" of the tail. [That's a good way to encapsulate "taillessness to near-taillessness to short-tailedness"! Use that term.]
- It is not the only defining characteristic of the breed. [Barton does not elaborate much, but Lane did; we now have two sources making it clear very early in the days of the "cat fancy" that Manx are distinctive in more than one way, and where Barton does specify, he does so in a consistent manner with Lane. I.e. this is a really good thing to double-up citations on.]
- Manx do not breed true; i.e. not every pure-bred individual exhibits all defining traits of the breed, like taillessness.
- This is also true of various, though not all, other pure-bred varieties of domestic animal, including [this took some outside reading] two canonically tail-suppressed dog breeds, the Bobtailed Sheepdog and the Schipperke, both of which are frequently born partially or fully tailed and are frequently tail-docked. [This is an interesting point, and even the fact that it's not all about cats is likely interesting to the reader; broadens the perspective.]
- Barton actually twice recommended docking of partially-tailed Manx, though he later also specifically states that this is sometimes done for fraudulent purposes. [And he even thinks that tailless cats are ugly; so he at least thinks of the breed as intrinsically a breed, albeit one he disfavors, rather than as defective cats.]
- Tail suppression is the most visually obvious of the breed's defining characteristics.
- Manx also have long back legs. [Other sources say this, but it's nice to have another source say it was an early, natural trait.]
- With short or no tail and long legs they thus have a rabbit-like rear half. [Lane and others said this too, but it's nice to have another early source indicating this was always the case, and always the perception.]
- Manx are of any [normal European cat] coat color. [Obviously not point colored or otherwise Asian; we know from Lane and, well, all other early cat fancy literature that in this era, Siamese and other "exotic" breeds were very rare curiosities in the West, and their genes were not being spread around yet.]
- Black was the most common color of the original, native Manx breed being written about at the turn of the last century, before controlled breeding of cats became a big deal. Lane corroborates. [We also have tentative info, not yet in the article, that this is actually no longer true even on the IoM, but once was.]
- Barton is actually quite hostile to the breed, and his derogatory remarks are worth quoting directly in full. They're a sharp counterpoint to Lane's enthusiasm (he owned one of the earliest championship Manx show cats), and are the earliest on-record cat expert hostility toward the breed. [This is a theme that actually carries through to the current day, and will soon be its own "Controversy" section in the article. This short little Barton piece is even more important than it seemed!]
- Docking of non-rumpy specimens was performed not long after birth. [This is no longer common practice today, and illegal in many places, including most of Europe.]
- Docking was sometimes performed for fraudulent purposes, to pass off regular cats as Manx by cutting their tails off. [We knew this already, but actually needed a source for it to add it to the article.]
A quick scan shows that what we can glean from and source to this article – what we can determinedly mine from it – is, in combination with other facts that have to be connected to and weighed against the details in this source, actually more material than the entire full text of the source! And that's before we've written it out in reader-friendly, explanatory prose.
After all of this is worked into the article, it's good to re-read the source; often a salient point will have been missed the first time around.
As this simple test case demonstrates, even sources that appear to be near-trivial in their brevity can often, if they are reliable, be used to source far more material than they seem capable of at first glance, especially if they relate (negatively or positively) to material in other sources. This remains true long after they are cited, since a newly "discovered" source may re-open a dynamic between the earlier, already-mined sources and the article as it evolves.
- Barton, Frank Townend (1908). "The Siamese—Abyssinian—Manx". The Cat: Its Points and Management in Health and Disease. London, England: Everett & Co. p. 31. Retrieved 2011-11-18.
 See also