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Re: st: difference-in-means for xt data

From   "Austin Nichols" <>
Subject   Re: st: difference-in-means for xt data
Date   Wed, 21 May 2008 20:26:24 -0400

Lloyd Dumont <>:
I would think it has more to do with how your data are -svyset-.  If
you provide some info on the survey design, you might get a better
answer, but I would define strata distinctly across rounds, make sure
weights are scaled appropriately (do you want to account for change in
pop size?), then -svy: regress- on an indicator for round.  Or -svy:
tab- versus round for indicator variables.

On Wed, May 21, 2008 at 7:24 PM, Lloyd Dumont <> wrote:
> Hello, everyone.  I wanted to examine a few variables
> for their differences-in-means over two rounds of a
> survey.  That is, for each variable, how has its mean
> changed between survey round I and survey round II?
> I can imagine how I would undertake the t-tests if
> these were two, disjoint cross-sections or if these
> were a balanced panel.  But, this is something in
> between.  Some respondents are only in the first
> round, some are only in the second, and some were
> actually surveyed twice.
> Since my data are xtset, I would guess there is a
> straightforward way to do this.
> Thanks for your thoughts, of course.  Lloyd Dumont
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