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st: RE: defining selection criteria


From   "Maarten Buis" <M.Buis@fsw.vu.nl>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: defining selection criteria
Date   Thu, 29 Mar 2007 11:00:57 +0200

--- Richard Pitman wrote:
> I have a dataset like the following
> 
> Id      week    class   treatment
> 1       0       2       a
> 1       8       3       a
> 1       12      3       a
> 2       0       3       b
> 2       8       3       b
> 2       12      4       b
> 3       0       3       a
> 3       8       3       a
> 3       12      2       a
> 
> I would like to cross tabulate treatment against class at week 12, ~but~
> only for those patients in class 3 at week 0. I am not sure how to achieve
> the last criteria.

What about this:

*-------------- begin example -----------
clear
input Id	week	class	 str1 treatment
1	0	2	a
1	8	3	a
1	12	3	a
2	0	3	b
2	8	3	b
2	12	4	b
3	0	3	a
3	8	3	a
3	12	2	a
end

reshape wide class , i(Id) j(week)
list, clean
tab treatment class12 if class0 == 3
*------------ 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 )

Hope this helps,
Maarten

-----------------------------------------
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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