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st: stepwise with if( exp)


From   Garry Anderson <g.anderson@unimelb.edu.au>
To   statalist@hsphsun2.harvard.edu
Subject   st: stepwise with if( exp)
Date   Thu, 23 Sep 2004 10:12:46 +1000

Hi Statalisters,

It seems that combining if( exp) with the sw command produces

varlist required
r(100);

For example,
use http://www.stata-press.com/data/r8/auto.dta

sw reg price mpg trunk if(mpg>20),pe(0.20)
varlist required
r(100);

reg price mpg trunk if(mpg>20)
produces results

sw reg price mpg trunk ,pe(0.20)
does forward selection, and produces results

sw reg price mpg trunk if (mpg>20),pe(0.20)
does forward selection, and produces results
(There is a space between if and the left bracket)

Therefore, it appears that -if(exp)- rather than -if (exp)- is causing the problem with the sw command. Hoever, -if(exp)- works with the reg command.

I am using the 23Jul executable and 01Sep updates.
Kind regards, Garry



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