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Re: st: RE: Binomial confidence intervals (more)

From   Richard Goldstein <>
Subject   Re: st: RE: Binomial confidence intervals (more)
Date   Mon, 13 Sep 2004 16:10:41 -0400

I was on vacation last week, but want to insert my 1.5 cents anyway:

The Yates corrected chi-squared is an approximation to Fisher. As such it is not as good as Fisher's exact test.

It has the same "disadvantage" as Fisher -- it is "conservative". I see no reason to ever use the Yates correction (unless you are all-of-a-sudden bereft of Fisher's exact test.

Rich Goldstein

Richard Williams wrote:

At 08:14 AM 9/9/2004 -0500, FEIVESON, ALAN H. (AL) (JSC-SK) (NASA) wrote:

All this discussion about failure of binomial confidence intervals to give
"exact" coverage also applies to the Fisher "exact" test, whose actual level
(probability of rejecting the null hypothesis of equal proportions, when in
fact the proportions are equal) is usually less than the nominal level,
depending on the true proprtions. In the frequentist setting, it's the same
problem - there are only a finite number of possible outcomes.

Al Feiveson

I was wondering about that. So, is there also a raging controversy over whether some alternative to Fisher is superior, e.g. Yates correction for continuity? Like Nick Cox said in an earlier post, it sounds like "exact" is more of a propaganda term than an accurate description of the test. (Kind of like saying you've got the "best" product on the market.)

Richard Williams, Notre Dame Dept of Sociology
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