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st: using weights with -svy- commands


From   Jeph Herrin <stata@spandrel.net>
To   statalist@hsphsun2.harvard.edu
Subject   st: using weights with -svy- commands
Date   Wed, 14 Mar 2012 11:48:41 -0400

All,

This seems like a question that has been asked & answered before, but I can't find it in the archives.

I have data which was was collected using a stratified survey design (NHANES, http://www.cdc.gov/nchs/nhanes.htm) which I have been analyzing using -svy- commands.

However, for a random subset of survey respondents, additional data is collected - up to 10080 motion counts collected each minute for up to 7 days. I have summarized these motion counts various ways for each respondent, but since not all respondents have the same reporting period, there is varying degrees of precision - some respondents have only a few thousand counts, some have the full 10k - and most importantly, I have found that the reporting period is associated with some of my key independent variables (in particular, overweight children have shorter reporting periods than normal weight children). So I want to incorporate the different precision of the summary outcome into my regression models.

In most linear regression models I would achieve this by weighting each observation by the inverse of the variance of the dependent variable measurement using -aweights-. However, -svy reg - does not support weights.

My questions are all due to the fact that I am a casual user of complex survey data. Is this because of a theoretical restriction due to the complex designs? Or is it a mechanical problem that I can somehow circumvent? Or is it possible with Stata, only I am overlooking the solution?

thanks,
Jeph
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