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Re: st: svy + aweights


From   Stas Kolenikov <skolenik@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: svy + aweights
Date   Thu, 10 Nov 2011 13:58:48 -0500

Rather than forming the mean activity per day, you might want to
analyze this as a ratio:

svy : ratio activity / day_reported

or whatever would be an appropriate ratio. That way, you will get
correct standard errors without messing with the analytical weights.

On Thu, Nov 10, 2011 at 1:46 PM, Jeph Herrin <stata@spandrel.net> wrote:
>
> I am analyzing NHANES data (see manual page for -svyset-) using -svy-
> commands. My complication is that I am using the subset of subjects for
> which there is activity monitoring, and the number of days monitored varies
> from 1 to 8. So - to be clear - for some subjects I have 1 day of
> monitoring,
> and for some I have 2 days, some I have 3, etc. My dependent variable of
> interest is daily average activity levels, but I would like this to be
> weighted by the number of days monitored. (This is important because there
> seems to be a clear relationship between days monitored and age, race, etc).
>
> How do I incorporate this additional level of weighting? For instance,
> if I use
>
>  svy : mean depvar [aw=days]
>
> I get an error that weights are not reported.
>
> thanks,
> Jeph
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>



-- 
Stas Kolenikov, also found at http://stas.kolenikov.name
Small print: I use this email account for mailing lists only.

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