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st: Re: using sample weights in the absence of stratification and clustering


From   "Scott Merryman" <smerryman@kc.rr.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: Re: using sample weights in the absence of stratification and clustering
Date   Thu, 14 Aug 2003 19:53:19 -0500

----- Original Message -----
From: frone@ria.buffalo.edu
Subject: st: using sample weights in the absence of stratification and
clustering
Date: Wed, 13 Aug 2003 19:00:18 -0400

> I would be grateful if someone could help me understand the basic issue
> involved in using sampling weights in the absence of stratification and
> clustering.

> If I compute the weighted mean and standard error of a variable in
> SPSS(using the sample weight)  or in Stata using -ci- and aweights, I get
> the same estimates for the weighted mean and standard error.  However, if
> I use -svymean- with pweights, I get the same estimate for the weighted
> mean, but the standard error is different.  There is a note on page 350 of
> [U] stating the standard error provided by SPSS or -ci- with aweights is
> not correct.  I'm not sure why.

<snip>

There is a discussion of weighted estimation at [U] 23.16 and in particular
[U]23.16.3.
aweighted estimation interprets larger weights to mean the data is more
accurately measured - pweights do not make this assumption.

Hope this helps,
Scott


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