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st: speed question: -collapse- vs -egen-


From   Jeph Herrin <junk@spandrel.net>
To   statalist@hsphsun2.harvard.edu
Subject   st: speed question: -collapse- vs -egen-
Date   Fri, 25 Apr 2008 15:37:21 -0400

I'm optimizing some code that needs to run often
for a simulation, and am wondering if I should
expect any difference in processing time between

 bys group: egen varmean=mean(myvar)
 bys group: keep if _n==1
 keep group varmean

and

 collapse (mean) varmean=myvar, by(group)

and if so, which would be faster?

I know I could run some tests myself, but figured
that others had either already done so or at least
would have some insight.

thanks in advance,
Jeph

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