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This is an old revision of this page, as edited by Melcombe (talk | contribs) at 13:32, 20 April 2013 (→Two distinct interpretations?: resp). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Article typical of much wiki nonsense -- instead of helping layman becomes evermore unavailable

Can anyone read the first several paragraphs of this article and understand it without having a good understanding of probability?

I actually have a BS in math, from 30 years ago, but since I haven't used it frequently, I am immediately put off by notation like P(A|B) WHICH IS NEVER DEFINED IN THIS ARTICLE.

I am sure this article only gets more and more precise and accurate.

DOES IT EVER GET MORE ACCESSIBLE TO THE LAYMAN?

Making articles ever more technical, and ever less accessible is a form of wiki rot and wiki masturbation.

The guideline covering these point is WP:MTAA. I recently updated much of the current article, which from my point of view is "one level down". However, maybe I misjudged that. I have just made some minor revisions that are hopefully improvements. I think you do have to be careful though, because trying to make things too accessible or too self-sufficient can detract from quality. For example, what exactly would you hope to take from an explanation of Bayes' theorem without mention of conditional probability or events? Should these things be explained in every article they are used? I think it is good to expect a particular body of knowledge, as long as readers are also clearly pointed to the prerequisites. Gnathan87 (talk) 22:43, 19 November 2011 (UTC)[reply]
I agree totally with the OP. I see this all over the place. It's useless to teach this way. I don't think it's typical of Wiki, but it is common. I call it "show-off writing."
I don't really have a great aptitude for reading or writing formulas. I know they're needed, but when mixed with complicated explainations, total confusion aboundsLonginus876 (talk) 12:32, 26 March 2013 (UTC)[reply]

An excellent figure

On the topic of making the article more accessible, I suggest using figure 2 of the article by Spiegelhater et al. 2011. The only problem is that it is probably copyright protected, but something similar should be easy to come up with (using your beetles example, for instance).

Spiegelhater, D., M. Pearson and I. Short. 2011. Visualizing Uncertainty about the Future. Science, vol. 333, pp. 1393-1400.

Spelling of Bayes's

I believe the proper grammar is Bayes's as opposed to Bayes'.

Nope, the proper way to make a noun ending in "s" possessive is to add an apostrophe without an additional "s". Hence "Thomas' shoes" and "Bayes' Theorem".
It is not that simple. Both New York Times and Oxford University Press write "Bayes's Theorem". Is "Bayes's" more British or more archaic version? I am not a native speaker, and I think I was taught to write "Charles's" many, many years ago... 82.181.47.81 (talk) 08:24, 24 June 2012 (UTC)[reply]

In the English language, the possessive of a singular noun is formed by adding apostrophe and s, regardless of whatever letter the word ends with, e.g., Thomas's pen. The possessive of a plural noun (such as Joneses) is formed by adding s and apostrophe, unless the word already ends in s, in which case just add apostrophe, e.g., the Joneses' house. The point is that apostrophe and s versus s and apostrophe marks a vital semantic distinction. The term Bayes' theorem thus correctly applies only to a theorem drafted by a group of people all named Baye. By contrast, Bayes's theorem denotes a theorem drafted by one person named Bayes.

Reverend Thomas Bayes was not a plural person, and his surname was not Baye.

Many Wikipedians will be inclined to cite any number of popular contrary uses as if they somehow made gratuitous confusion between singular possessive and plural possessive to be acceptable. Sadly, one of those uses would the title of Sharon Grayne's excellent book on the good Reverend's work. To those Wikipedians I would say: How do you distinguish between recording of specie (payment, singular) and recording of species (types, plural), if you'd say species' recording for both?

(It's possible that specie in that sense is a mass noun, not countable, but it's difficult to think offhand of a pair of good common nouns for this illustration, but I hope the point is clear anyway.)
(The unsigned comment added by 208.88.176.15 (talk) 1 November 2012)

I agree that proper use is Bayes's rather than Bayes', whereas the latter could be quite common due to popular confusion or mis-application of grammar rules. Most respected traditional English language grammar styles would unambiguously agree on "Bayes's". I'll go ahead and make changes unless there's a good overwhelming evidence that the current version (Bayes') is one of the few rare exceptions. cherkash (talk) 00:18, 26 January 2013 (UTC)[reply]
Don't ignore the preceding dscussion at http://en.wikipedia.org/wiki/Talk:Bayes%27_theorem/Archive_1#Spelling_of_of_possessive_ending_in_.27s.27 Further. a typical grammar book says "names ending in "-es" pronounced iz are treated like plurals and take only an apostrophe ..." (Oxford English, OUP). 81.98.35.149 (talk) 23:50, 27 January 2013 (UTC)[reply]
You will need to provide a better reference, the one you gave is very vague (is "Oxford English" a book? who's the author? ISBN?). The reference you alluding to is also dubious, as according to it Jones's should be Jones', etc. – which is not the case that most manuals of style would agree with. Besides, the above argument on Baye's and Bayes' is as reasonable as anything you could find in support of proper English grammar. Further, although some speakers may prefer to pronounce Bayes's as Bayes' (the main argument that most proponents of using loose rules on possessives would allude to), there's clear value to adhere to Bayes's in writing as it avoids ambiguity between plural and singular possessives. cherkash (talk) 01:22, 28 January 2013 (UTC)[reply]
The ref has isbn 0198691696, which is better detail than antyhing you have provided. You clearly haven't taken on board the difference in pronouncation between Jones and Bayes, which is of some importance. In particular, everyone says "Bayes theorem", rather than "Bayeses theorem". Further, Wikipedia rules are to follow the general usage within the general field concerned, here statistics and probability, rather than to impose some global set of rules for supposed uniformity. The fact is that general usage in statistics and probability is Bayes' theorem. 81.98.35.149 (talk) 08:44, 28 January 2013 (UTC)[reply]
Both spellings are acceptable in British English but Bayes' is far more common for this subject. Martin Hogbin (talk) 14:57, 22 March 2013 (UTC)[reply]

Introductory example - Sexism?

The sentence reads: "If he told you the person he spoke to was going to visit a quilt exhibition, it is far more likely than 50% it is a woman. " Clearly, in our modern society this is sexist, as men are just as likely to go to quilt exhibitions. I don't think that Wikipedia should be biased. — Preceding unsigned comment added by 129.215.5.255 (talk) 14:12, 12 April 2012 (UTC)[reply]

I don't know about sexist, but it could certainly do with being more explicit. Add, for example, that you read in the paper that 95% of quilt conference attendees are female, and you have something that relies less on your individual assumptions about gender roles and more on a rational interpretation of known facts. ...BTW, there are quilt conferences? I have never heard of this. — Preceding unsigned comment added by 184.187.186.33 (talk) 23:41, 24 May 2012 (UTC)[reply]
Shouldn't the question be "what percentage of people with long hair are women"? Not what percentage of women have long hair. Or are these recipricals of each other. I don't really understand these things very well. It's just a question.Longinus876 (talk) 12:15, 26 March 2013 (UTC)[reply]
P(W|L) and P(L|W), the chance someone with long hair is a woman and the chance a woman has long hair, are two different things and Bayes' theorem shows how they are related. In fact, P(W|L)/P(L|W)=P(W)/P(L). That's the whole point. Richard Gill (talk) 10:52, 20 April 2013 (UTC)[reply]

Incidentally, the example shows yet again that it is easier to explain Bayes to laypersons using the Bayes' rule version rather than the conventional Bayes' theorem version. I think the reason why conventional elementary textbooks use the clumsy and unintuitive formula rather than the simple and intuitive Bayes rule is because they are uncomfortable with using the concept of "proportionality" and scared of using the concept of "odds". However, both when explaining Bayes to laypersons, and in modern applications in science, statistics, information technology ... It is Bayes' rule which we use, every time. Richard Gill (talk) 11:16, 20 April 2013 (UTC)[reply]

Spelling

If English spelling demands Bayes's theorem is spelled this way, we should correct this anywhere it is necessary. Nijdam (talk) 11:43, 19 November 2012 (UTC)[reply]

No comment? Nijdam (talk) 16:49, 10 December 2012 (UTC)[reply]

See a few sections above. 81.98.35.149 (talk) 23:51, 27 January 2013 (UTC)[reply]

Bayes' Rule vs Bayes' Theorem

The correct way in English to express the possessive when a name ends in an s is by a single apostrophe after the s which is already there. See for instance http://www.cs.ubc.ca/~murphyk/Bayes/bayesrule.html, http://plato.stanford.edu/entries/bayes-theorem/

The text on Bayes' rule said that it depended on the Bayesian interpretation of probability but that is not true. Bayes' rule is equivalent to Bayes' theorem and both are valid for any probability interpretation. The equivalance is a mathematical fact which follows from the normalization of probability. If a probability space is partitioned into some events A, B, C, ... and you know the probabilities of A, B, C ... up to proportionality, then you know them absolutely, you just have to divide by the sum of what you already have. Richard Gill (talk) 13:23, 22 March 2013 (UTC)[reply]

Two distinct interpretations?

The lead io the article starts by saying that Bayes' theorem has two distinct interpretations. I think this is hardly true, and not important. Bayes' theorem is an elementary identity following from the definition of conditional probability (and, in some forms, the law of total probability). The article refers to distinct interpretations of probability, not of the theorem! Richard Gill (talk) 10:38, 20 April 2013 (UTC)[reply]

Lead rewritten. Better? Note that this article originated in a way that mixed Bayes' theorem with Bayesian inference, and so some aspects of this may linger. Melcombe (talk) 13:32, 20 April 2013 (UTC)[reply]

Bad introductory example

The introductory example is badly chosen. It is a numerical coincidence that in this case, P(W|L) turns out to be equal to P(L|W). Yet typical readers are struggling to understand and distinguish the different concepts behind these notations.

The example shows yet again, that to explain these things to newcomers, Bayes' rule is much better than Bayes' theorem: more insight, less blind calculation. Richard Gill (talk) 11:24, 20 April 2013 (UTC)[reply]

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