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Re: st: Survival analysis


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Survival analysis
Date   Tue, 1 Sep 2009 19:50:45 +0000 (GMT)

--- On Tue, 1/9/09, moleps islon wrote:
> http://picasaweb.google.no/moleps2/Skrivebord#5376581559320130946

This is the wrong graph to assess whether the proportional hazard 
assumption is violated. You need to use -stphplot- instead  (see:
-help stphplot-). 

Anyhow, I don't think that -stcox- is applicable in your case. 
-stcox- assumes that everybody eventually experiences the event, 
and those that haven't experienced it in the study period will 
do so later. However in your case a substantial proportion 
(60-75%) appears to be cured (flattening of the hazard curve). 
See: Paul C. Lambert (2007) Modeling of the cure fraction in 
survival studies. The Stata Journal, 7(3): 351-375.
http://www.stata-journal.com/article.html?article=st0131

Hope this helps,
Maarten

--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://www.maartenbuis.nl
--------------------------



      

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