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Re: st: discrete time-varying covariate in cox models


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: discrete time-varying covariate in cox models
Date   Tue, 13 Nov 2007 10:26:44 +0000 (GMT)

--- "Daniel O. Koralek" <dkoralek@unc.edu> wrote:
> Now, what I would like to do is simply control for a single screen  
> variable that equals the number of screens that occurred up to the  
> analysis time.  THe examples that I have seen using stsplit seem to  
> only use a single change (in this scenario, up to a certain point  
> screen =0 and after screen = 1), not where multiple changes can
> occur.

If a single change occurs than you create a dummy after -stsplit-, if
you have multiple changes you add multiple dummies, or if you
hypothesis a linear effect, a single continuous variable. In all these
cases -stsplit- doesn't know or cares which scenario applies, it works
in exactly the same way. 

-- 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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