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Re: st: RE: r2 in -streg-/-stcox-


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: r2 in -streg-/-stcox-
Date   Fri, 6 Oct 2006 20:32:44 +0100 (BST)

--- Nishant Dass <nishant_dass@yahoo.com> wrote:
> why does the data of Hosmer and Lemeshow (that you use in your
> note as well) mainly consist of categorical covariates and
> not continuous variables?  Do continuous variables not lend
> easily to survival analysis?  

Nishant:
There is no problem with using continuous variables in survival
analysis other than the assumption that the effect on log hazard or log
time (depending on your model) is linear. This is of course no
different from any other model that allows continuous variables. 

The only exception is if you want to compare the Kaplan Meier survival
curves of different groups. In that case you will have to use a
categorical variable. This is why in my example on Kaplan Meier
estimates I use the distinction between poor and rich countries, and
GDP per capita (a continuous variable) for -streg- and -stcox- models.
HTH,
Maarten

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

visiting adress:
Buitenveldertselaan 3 (Metropolitan), room Z434

+31 20 5986715

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


		
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