W3C home > Mailing lists > Public > public-html@w3.org > February 2009

Re: summary="" in HTML5 ISSUE-32

From: Maciej Stachowiak <mjs@apple.com>
Date: Thu, 26 Feb 2009 17:37:44 -0800
Cc: Ian Hickson <ian@hixie.ch>, Steven Faulkner <faulkner.steve@gmail.com>, HTMLWG <public-html@w3.org>, W3C WAI Protocols & Formats <w3c-wai-pf@w3.org>
Message-id: <272DD053-A9EF-473F-9C68-1EB67730A800@apple.com>
To: Philip TAYLOR <P.Taylor@Rhul.Ac.Uk>

On Feb 26, 2009, at 3:20 PM, Philip TAYLOR wrote:

> Ian Hickson wrote:
>>> Doesn't that require that both samples be taken from the same  
>>> homogeneous population ?
>> The fact that first two points are so closely correlated means that  
>> the two samples probably are both proportional samples of the same  
>> overall population, which is why we can draw the conclusion from  
>> the third data point from only one sample.
> We are getting dangerously off-topic, but I disagree.
> There may well be a correlation between the prevalence
> of lemons and the prevalence of cones, yet no such
> correlation between (the prevalence of) either lemons
> and apples  or between cones and apples.

If two independent population samples show similar distribution of  
many characteristics, Bayesian inference would lead us to conclude  
that they are likely (though not certain) to show similar distribution  
of other characteristics. This is particularly the case with traits  
that are not fully independent but likely to correlate with each  
other. If we had evidence that one sample or the other had a  
systematic selection bias relating to the characteristic in question,  
we might conclude otherwise.

Received on Friday, 27 February 2009 01:38:46 UTC

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