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st: First occurence


From   "Meryle Weinstein" <mgw216@nyu.edu>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: First occurence
Date   Thu, 17 May 2007 09:24:54 -0400

I've tried following the syntax in FAQ and archives but am having difficulty
with it.  I have a dataset that has an idcode and a year for a number of
schools.  I want to identify the first year that the idcode appears.  I've
tried the following but still don't' get the first occurrence.

by bdsmaster (year), sort: gen noccur = sum(bdsmaster)
by bdsmaster: gen byte first = noccur == 1  & noccur[_n - 1] != noccur

gen byte first = sum(bdsmaster == 1) == 1  & sum(bdsmaster[_n - 1] == 1) ==
0  

Thanks for your help.

Meryle Weinstein
Research Scientist
Institute for Education & Social Policy
New York University
Pless Hall
82 Washington Square East, 7th floor
New York, NY 10003
(212) 998-5817
(212) 995-4564 (fax)
www.steinhardt.nyu.edu/iesp



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