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st: RE: programming in Stata


From   "Maarten Buis" <M.Buis@fsw.vu.nl>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: programming in Stata
Date   Thu, 15 Mar 2007 11:34:05 +0100

--- Ali Khashan wrote:
> I have a large dataset similar to this:
> mother_number         child_number  GA     nDate            suggested var
> 1234567891            23456789      35     21 Feb 1975       .
> 1234567891            23456781      37     30 May 1978       35
> 1234567891            23456782      40     04 Oct 1982       37
> 1234567892            56789012      37     17 Mar 1976
> 1234567893            56489023      40     23 Sep 1985
> 1234567894            34567891      40     19 Nov 1977
> 1234567894            45567890      42     13 May 1979
>
> From mother_number you can see that some women have more than one child (they
> have the same identification number). GA is gestational age and nDate is date
> of birth of the child. I need to generate another variable which indicates
> gestational age of the previuos child.


*---------------------- begin example ------------
clear
input double mother_number double child_number GA 
1234567891            23456789      35    
1234567891            23456781      37    
1234567891            23456782      40    
1234567892            56789012      37    
1234567893            56489023      40    
1234567894            34567891      40    
1234567894            45567890      42    
end

bys mother_number (GA): gen prevGA = GA[_n-1]
list
*-------------------- end example -------------------
(For more on how to use examples I sent to the Statalist, see 
http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )

-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology 
Vrije Universiteit Amsterdam 
Boelelaan 1081 
1081 HV Amsterdam 
The Netherlands

visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434 

+31 20 5986715

http://home.fsw.vu.nl/m.buis/
-----------------------------------------



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