Re: st: svy + aweights

[Jeph Herrin <stata@spandrel.net>]

Thanks for the suggestion, but I specifically need to give more
weight to subjects which have more days of observation. For example,
I have

   svy : regress activity female BMI

and would like this regression to give more weight to subjects which
have more days of observation. Using activity/days as the dependent
variable will not do this.

Jeph

On 11/10/2011 1:58 PM, Stas Kolenikov wrote:
> 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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