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RE: st: Ritesh's Inquiry (correction)


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Ritesh's Inquiry (correction)
Date   Sat, 5 Jul 2003 22:51:19 +0100

Sorry, I need to correct the code just posted: 

In Stata terms this is, with a group structure:
 
bysort group : gen newvar = sum(score)
by group : replace newvar = (newvar[_N] - score) / (_N - 1)
 
There could be at least one problem with
this, any missing values in -score-.
 
The extra wrinkle to cope with that is
something like
 
bysort group : gen newvar = sum(score)
by group : gen N = sum(score < .)
by group : replace newvar = (newvar[_N] - score) / (N[_N] - 1)

or like
 
bysort group : gen newvar = sum(score)
by group : egen N = count(score)
by group : replace newvar = (newvar[_N] - score) / (N - 1)

Nick
n.j.cox@durham.ac.uk

P.S. another way to do it 

bysort group : egen newvar = sum(score)
by group : egen N = count(score)
by group : replace newvar = (newvar - score) / (N - 1)

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