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st: How to set calibrated weights


From   Veronica Galassi <veronicagalassi@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: How to set calibrated weights
Date   Fri, 19 Oct 2012 18:57:47 +0100

Dear Statalisters,

I am writing you concerning the application of calibrated weights to
my dataset for the computation of descriptive statistics only.

The dataset I am working on collects information at household and
individual level and comes from a stratified, two-stage clustered
sample. The followings are the variables I have got:
- probability weights: w2_dwgt
- strata: w2_gc_dc
- cluster 1: w2_gc_prov
- cluster 2: w2_hhgeo
- post-stratified weights: w2_wgt
- age intervals:  w2_age_intervals
- gender: w2_best_gen
- population group: w2_best_race

In order to set the probability weights using the command svyset, I
need the psu variable. As you may have noticed, this variable is
missing and this makes me impossible to set pweights.
In addition, from a couple of previous statalist conversations ( see
in particular: http://www.ats.ucla.edu/stat/stata/faq/svy_stata_post.htm
and http://www.stata.com/statalist/archive/2012-02/msg00584.html), I
understood that:
- when using calibrated weights I still have to set pweights and
specify the original strata and clusters
- In order to apply calibrated data I need to know the characteristics
on the base of which the sample have been post-stratified ( in my case
age intervals, gender and population groups).

Therefore, I tried to set my post-stratified weights using the
following command:
"svyset [pw=w2_dwgt], strata (w2_gc_dc) poststrata (w2_age_intervals
w2_best_gen w2_best_race) postweight(w2_wgt)"
which did not work because in Stata the poststrata must be mutually
exclusive and thus only one variable can be specified.

In order to overcome this problem, I tried to generate a variable
which is a combination of the three characteristics by using the
command
"egen combination=concat( w2_age_intervals w2_best_race w2_best_gen),
format (float)".
However, this command generated a variable containing only missing
values and for this reason Stata gave me back the error:
"option postweight() requires option poststrata()".
The only way to make Stata set the post-calibrated weight was by using
the command
"svyset, poststrata (combination) postweight(w2_wgt)" with combination
being a string variable. However I am scared that this command is not
complete.

At this point, I would really appreciate any hint on what I am doing
wrong and how to proceed to set my post-stratified weights.

Many thanks for your help!

Kind regards,

Veronica Galassi
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