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Re: st: svy subpop option and e(sample)


From   Steven Samuels <sjsamuels@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: svy subpop option and e(sample)
Date   Wed, 25 May 2011 17:13:35 -0400

I'm going to withdraw my statement that inappropriate weights are a problem for subpopulation analysis, Richard.  I could be wrong. On closer examination the Levy-Lemeshow example would probably not occur in practice.
I have seen weights behave badly, but not because of a sub-population analysis per se'.  I'll have to look into this some more, and  I apologize  for making such a strong statement without better evidence to back it up.

Steve

On May 25, 2011, at 4:19 PM, Richard Williams wrote:

At 02:03 PM 5/25/2011, Steven Samuels wrote:
> --
> 
> I have to agree with Stas.  While the standard errors from subsetting and from using -subpop()- might be indistinguishable, it is not a given. My example was simplistic: there were no strata, and clusters were independent of the subpopulation, weight, and analysis variables.
> 
> Another, potentially more serious, problem for subpopulation analysis is not, I believe, mentioned in the SJ article: bias can arise if the supplied weights, appropriate for the whole sample, are wrong for the subpopulation. Levy & Lemeshow (2008, p.148) give a simple example.

Thanks to both you and Stas. Just so I am clear, would this be a problem even if using the subpop option, or only if using an extract?


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Richard Williams, Notre Dame Dept of Sociology
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