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Re: st: AW: population weights question

From   Kyleigh Schraeder <>
Subject   Re: st: AW: population weights question
Date   Tue, 21 Feb 2012 13:26:42 -0500

I want to compare the clinic sample with the national sample (which
should be representative of the general population).  To assess the
comparability between the two datasets on a single given item, I want
to calculate relative risk ratios for each variable.

For each item, I would like to examine any gender differences within
and between the clinic dataset and the national dataset. Does that
answer your question?


On Tue, Feb 21, 2012 at 1:10 PM, Reinhardt Jan Dietrich
<> wrote:
> Do you want to compare your clinical sample with the general population or with your national sample? Do you want to compare the effect of gender on some outcome between the two groups, the prevalence of some trait or something else?
> All this is important to know in order to decide if the weights for the national sample should be used or not in the comparative analysis (anyway, the weights for your clinical sample would always be 1).
> Jan
> ________________________________________
> Von: []&quot; im Auftrag von &quot;Kyleigh Schraeder []
> Gesendet: Dienstag, 21. Februar 2012 18:28
> An:
> Betreff: st: population weights question
> Hi statalisters,
> Steven helped me out with a similar question the other day but I would
> like to rephrase.
> I would like to compare a national health survey dataset to an
> independently collected clinic dataset.  The clinic dataset was not
> weighted.  I am having some difficulty understanding how to employ the
> complex survey variables that were employed for the national dataset.
> The design variables for the national dataset are:
> xwgtreg (sampling weight variable)
> strata (strata variable, 19 strata)
> schlid (primary sampling unit/cluster - school id number)
> Although national health survey data was collected from a
> representative sample of grade 7-12 students (N exceeds 7,000
> students), I only want to look at students between the ages 15-19 from
> one stratum (stratum 19).  I am also interested in gender differences
> between the national dataset and clinic dataset.  I am wondering how
> to (and if I need to) -stset- the national health survey data for
> analysis.  I have used the following commands:
> use nationaldataset
> keep if strata==19
> keep if Age==16|Age==17|Age==18|Age==19
> svyset schlid [pweight=xwgtreg], strata(strata)
> **Then I ran tabulate and other descriptive commands. In order to
> calculate appropriate variance estimates/confidence intervals, and
> p-values, I have created subpopulations for gender analyses.  I read
> that this step is necessary when analyzing survey data using compex
> survey procedures..?*
> gen Subpopmale = .
> label variable Subpopmale "Subpopulation1: males 16 to 19 years old"
> replace Subpopmale = 0 if (Gender == 2)
> replace Subpopmale = 1 if (Gender == 1)
> label define Subpopmale 1 "male" 0 "female"
> label values Subpopmale Subpopmale
> svy, subpop(Subpopmale): tabulate Mother_education
> svy, subpop(Subpopmale): tabulate Father_education
> **In order to compare the national health survey dataset to the clinic
> dataset, I have used the following commands
> use clinicdataset
> append using nationaldataset
> replace samptype = 2 if sample==.
> label define samptype 1 "clinic" 2 "national"
> label values samptype samptype
> svyset schlid [pweight=xwgtreg], strata(strata)
> Can I just go ahead and run comparative analyses (relative risk
> ratios) on this combined dataset? I don't quite understand if the
> population weights are being accounted for by the national dataset. .
> Thanks in advance for your help,
> Kyleigh
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