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Re: st: Query re proportions post-standardization


From   Philip Burgess <philip.burgess.uq@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Query re proportions post-standardization
Date   Mon, 16 Nov 2009 11:00:56 +1000

Dear all;

I've sorted out this issue. It was not a Stata issue but a problem
with how I had set up the standard populations.

Apologies for any distraction.

Thanks;

Philip

On Sun, Nov 15, 2009 at 9:14 AM, Philip Burgess
<philip.burgess.uq@gmail.com> wrote:
> I have a dataset with 2 cross-sectional independent samples - the
> first survey conducted in 1997 & the second survey conducted in 2007.
> The var indicating survey year is nsmhwb - coded (0/1).
>
> My svyset statement, based on the 90 jackknife replicate weights etc,
> is as follows:
>
> -svyset [pweight=mhsfinwt], jkrweight(wpm0101 - wpm0190,
> multiplier(1)) vce(jackknife) mse-
>
> I want to compare proportions on a DV (mhpsyo12 = 0/1) by IV survey
> year (nsmhwb = 0/1).
>
> -svy jackknife, nodots : proportion mhpsyo12, over(nsmhwb)-
>
> The 1997 estimate is 17.0% (SE = 1.3%)' the 2007 estimate is 37.3% (SE = 2.5%).
>
> I have separately created a variable that indicate the proportion of
> 2007 in each of 5 age group strata (i.e., 20-29 years, 30-39 years,
> etc to 60-69 years). The strata var is 'st_age)'; the 2007 strata
> population proportion var is 'st_wt' - ranging from 0.0 to 1.0.
>
> The population structure has changed over the 10-year period (i.e.,
> aged). So, I want to compare proportions adjusted by the 2007 strata
> population size I run:
>
> svy jackknife, nodots : proportion mhpsyo12, stdize(st_age)
> stdweight(st_wt) over(nsmhwb)
>
> The 1997 estimate is 15.5% (SE = 1.4%)' the 2007 estimate is 34.1% (SE = 2.3%).
>
> I'm puzzled that the 2007 proportion estimates change from the
> previous statement. I would have thought that the 2007 estimates (and
> their SEs) would NOT vary given the fact that standardization is based
> on actual 2007 proportions?
>
> I guess I'm doing something wrong - any ideas?
>
> I'm using Stata 11.0 - born 21 October 2009.
>
> Thanks;
>
> Philip
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