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st: Dealing with survey data when the entire population is also in the dataset

From   Margo Schlanger <>
Subject   st: Dealing with survey data when the entire population is also in the dataset
Date   Fri, 24 Jul 2009 19:06:33 -0400

Hi --

I have a dataset in which the observation is a "case".  I started with
a complete census of the ~4000 relevant cases; each of them gets a
line in my dataset.  I have data filling a few variables about each of
them.  (When they were filed, where they were filed, the type of
outcome, etc.)

I randomly sampled them using 3 strata (for one strata, the sampling
probability was 1, for another about .5, and for a third, about .75).
I end up with a sample of about 2000.  I know much more about this

Ok, my question:

1) How do I use the svyset command to describe this dataset?  It would
be easy if I just dropped all the non-sampled observations, but I
don't want to do that, because of question 2:

2) How do I compare something about the sample to the entire
population, just to demonstrate that my sample isn't very different
from that entire population on any of the few variables I actually
have comprehensive data about. I could do this simply, if I didn't
have to worry about weighting:

tabulate year sample, chi2

But I need the weights.  In addition, I can't simply use weighting
commands, because in the population (when sample == 0), everything
should be weighted the same; the weights apply only to my sample (when
sample == 1).  And I can't (so far) use survey commands, because I
don't know the answer to (1), above.

NOTE: Nearly all the variables I care about are categorical:  year of
filing, type of case.  But it's easy enough to turn them into dummies,
if that's useful.

Thanks for any help with this.

Margo Schlanger

Professor of Law
University of Michigan Law School
Director, Civil Rights Litigation Clearinghouse

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