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Re: st: Survey analysis: Why does PSU affect proportions?


From   "Austin Nichols" <austinnichols@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Survey analysis: Why does PSU affect proportions?
Date   Mon, 10 Jul 2006 20:38:50 -0400

Craig--
Your number of obs changed when including PSU/stratum vars.
Try -codebook psu strat- to see # of missing values, etc.

On 7/10/06, Craig Anderson <clanders@uci.edu> wrote:
I am using a published dataset (from CDC) and I want to verify that I
can duplicate the published results before I begin my analysis.  I
found that including clustering and stratification variables changed
proportions, not only standard errors.  In the output that follows, I
first used only the weights.  This gives results that agree with the
published estimates of the proportions (produced using SUDAAN).  Next
I used the PSU and STRATA, and get different proportions, but
confidence intervals that agree with the published results, with
minor variations in other runs.  I don't think the clustering by
strata and psu should influence proportions, only their variance.
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