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Re: st: RE: Command "margin" after Cox Regression


From   "Weichle, Thomas" <Thomas.Weichle@va.gov>
To   <statalist@hsphsun2.harvard.edu>
Subject   Re: st: RE: Command "margin" after Cox Regression
Date   Wed, 26 Oct 2011 11:49:48 -0500

Hi Yuval,
The baseline survival is calculated for every observed event time in the
dataset for the reference group (those subjects with
all covariates=0). Based on your example, you calculated a baseline
survival for the model which included max_red1. Another baseline
survival is calculated for the model which included max_red2.  These
baseline survivals are different because the reference group represents
something slightly different when you generated max_red1 and max_red2.
This variation in baseline survival, I believe, does modify the survival
rates.

Tom Weichle
Math Statistician
Center for Management of Complex Chronic Care (CMC3)
Hines VA Hospital, Bldg 1, C202
708-202-8387 ext. 24261
Thomas.Weichle@va.gov 


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