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st: Duplicate combinations of variables
From
Miranda Kim <[email protected]>
To
[email protected]
Subject
st: Duplicate combinations of variables
Date
Thu, 25 Mar 2010 14:18:09 +0000
Hello,
I am a Stata 11 user, and I wonder if anyone has advice on achieving the
following:
I have two variables, one with ID numbers for cases and one with ID
numbers for matched controls in a case control study. There are 3
controls matched to each case, and a subject may serve as a control for
more than one case or later become a case. I am wanting to check that in
my dataset all the pairs of cases and their matched control are unique;
ie that I don’t have for example:
Case ID Control ID
123 253
253 123
Any suggestions would be of great help!
Many thanks and best wishes,
Miranda
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