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Re: st: RE: How to do domain analysis in svy:reg or svy:glm?


From   Stas Kolenikov <skolenik@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: How to do domain analysis in svy:reg or svy:glm?
Date   Mon, 26 Oct 2009 16:47:30 -0500

-over- and -by- in the original request are likely the legacy of SAS.
Domain analysis is performed with -subpop()- option, and is well
documented.

On 10/26/09, Nick Cox <n.j.cox@durham.ac.uk> wrote:
> I leave all -svy- questions to the savvy, but there's apparently a simple misconception here.
>
>  You can get separate regressions by using -by:- as a prefix command. Expecting -by()- and -over()- to work as options is not surprising if you've ingested graphics syntax, but the logic is different for regressions and the syntax certainly is.
>
>  by <whatever> : <somecommand>
>
>  produces separate results.
>
>  <somecommand>, by(<whatever>)
>
>  produces composite results. At least it should be something like that.
>
>  Nick
>  n.j.cox@durham.ac.uk
>
>  CHEN HSINJEN
>
>  My aim is to do stratified regression analysis while accounting for
>  the complex sampling design, i.e. to estimate the relationship between
>  BMI and age, separately in women and men.
>  However, the "reg" and "glm" commands do not allow "over", or even "by", option.
>
>  For example, the following statement is not allowed.
>
>       svy: reg BMI age, over(sex)
>
>  Thus, we may want to solve this by using "if":
>
>      svy: reg BMI age if sex == 1 *(for men)
>      svy: reg BMI age if sex == 2 *(for women)
>
>  But, the problem is, when sex == 2, some strata have only one cluster
>  (or some clusters have only one observations.) And then, the S.E. is
>  not estimated by stata.
>
>  How can I get unbiased estimate of regression coefficient and its S.E.
>  under this circumstance?
>  Is this solvable in stata?
>
>  *
>  *   For searches and help try:
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>  *   http://www.ats.ucla.edu/stat/stata/
>


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