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st: Duplicates drop


From   "Thomas Speidel" <thomassp@cancerboard.ab.ca>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: Duplicates drop
Date   Wed, 1 Jun 2005 12:35:14 -0600

When using duplicates drop, Stata will keep the first occurrence and
drop any subsequent ones.  If you want to selectively drop specific
duplicates, then I suggest you do it manually, for example:

bysort id: gen dup=_n
gen dup2="YES" if dup>1
replace dup2="NO" if dup==1

then, you can selectively drop the observations you want according to
the value of some other variable, for example:

drop if dup2=="YES" & some_variable=="something_value"

Hope this helps,
Thomas

Thomas Speidel
Statistical Associate
Department of Oncology
Tom Baker Cancer Centre
1331 - 29th Street N.W.
Calgary, AB, T2N 4N4

Tel. (403) 521-3370
Email: thomassp@cancerboard.ab.ca

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