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st: comparing 2 surveys; testing means and distributions; using weights


From   Marie-Hélène Felt <marie-helene.felt.1@ulaval.ca>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   st: comparing 2 surveys; testing means and distributions; using weights
Date   Wed, 27 Jun 2012 20:58:20 -0400

Hello all,
I am working on comparing 2 independent survey datasets that stem from relatively close questionnaires (done same year, in Canada with national representativity targetted). I have some doubts about how to proceed using Stata. 
Sampling weights are supplied in both datasets. They are constructed based on demographic targets such as age, income or city size (these targets variables differ across surveys). I don't think there is any cluster or strata. 

My questions:
1) I wasn't sure to be allowed to combine both datasets into a sigle 1, but from what I have read in the Statlist archive I can do just that and create 2 strata indicating the 2 surveys? Will Stata understand that there are 2 surveys/ won't Stata mess up weights? 

2) the weights, as provided, are not scaled the same way. For one dataset, the mean is one and so the represented population size equals the sample size (around 5000). For the other dataset, the weights are such that the population size is huge (around 20,000,000). Is that an issue? Should I rescale these last weights? 

3) My goal is to compare answers/variables of the 2 surveys/datasets. I want to first test if means or proportions differences across surveys are significant. Once I have combined both datasets, can I just do t tests between groups [groups that are also strata]? 

4) I would also like to test equality of distributions, not only means. I know the mgof command for categorical variables.Is there a way to test continuous distributions taking weights/the survey dimension into account?

thanks a lot in advance for your tips!

MHF


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