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st: RE: Tab, chi2 using weights


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Tab, chi2 using weights
Date   Mon, 10 May 2004 19:19:20 +0100

I guess that you're going to have to program 
this yourself, taking responsibility for 
how you calculate df and thus P-value. 
As it happens, it seems that -chi2tail()- 
works as one would hope for non-integer df. 

Or would a log-linear model with 
importance weights be equivalent 
for your underlying scientific problem? 

Nick 
n.j.cox@durham.ac.uk 

Pierre-Antoine Kremp
 
> I'm using a dataset with "importance weights": frequency weights
> multiplied by the sampling rate n/N -- so that the sum of those
> importance weights equals the sample size n, not the target population
> size N) and I'd like to do a Pearson chi-squared test on a 2-way
> contingency table. It shouldn't be too hard, but the chi2 
> option of the
> tab command doesn't accept iweights. Only integer frequency 
> weights seem
> to be allowed. I could very well use frequency weights 
> instead, but that
> would increase the Chi2 stat unreasonably.
> 
> Any idea on how to get round this problem?
> 
> Thanks a lot (and sorry if the question is too trivial!)

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