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RE: AW: st: Chi-squared test for independence of observed and expected frequencies


From   "Lachenbruch, Peter" <Peter.Lachenbruch@oregonstate.edu>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   RE: AW: st: Chi-squared test for independence of observed and expected frequencies
Date   Fri, 16 Jul 2010 11:32:56 -0700

However, one may want to test subtables when the overall hypothesis is one of homogeneity of various populations.  The second test is one of independence.  For a full table, the two tests are identical.  When one is looking at subtables one is in the multiple testing mode.  The way to do this is to look at the likelihood ratio chi-square and compare to the critical value for the full table (i.e. (r-1)(c-1) for the full table) even if one is looking at a 2x2 subtable
I don't have the exact reference, but it is fairly old -either something by Novick and Grizzle in JASA or Gabriel in Annals of STatistic.  It is before 1980 - if there's demand for this, i can look it up next week.

________________________________________
From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] On Behalf Of Maarten buis [maartenbuis@yahoo.co.uk]
Sent: Friday, July 16, 2010 1:36 AM
To: statalist@hsphsun2.harvard.edu
Subject: Re: AW: st: Chi-squared test for independence of observed and expected frequencies

--- On Fri, 16/7/10, Marc Michelsen wrote:
> Do you have any idea how the authors have tested
> the significance of each of the frequencies?

I don't even know what the null hypothesis should be:
independence refers to the whole set of frequencies
that make up a cross tabulation. A test on individual
frequencies then just does not make sense within
this context.

-- Maarten

--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://www.maartenbuis.nl
--------------------------






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