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Re: st: cox regression values


From   Maarten Buis <maartenlbuis@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: cox regression values
Date   Thu, 23 Feb 2012 16:09:22 +0100

On Thu, Feb 23, 2012 at 3:34 PM, Luisa Soares-Miranda wrote:
> When I am doing a cox regression as for exemple  xi: stcox ib0.A  B C
> D G H , and if in variable A I have 3 groups how can I know what is
> the exact hazard ratio values for each group of variable A.

With Cox regression you cannot, nor do you want to. You can only know
the hazard ratios for two out of three groups. The reason is that with
-stcox- you are deliberately not estimating the baseline hazard, so
you always have to exclude one reference category. This is both a
strength and a weakness of Cox regression; on the one hand if you do
not estimated it than you cannot make an error, but on the other hand
sometimes you want to know the hazards instead of the hazard ratios.

Hope this helps,
Maarten

Ps. you are combining factor variable notation with the -xi- prefix.
That looks like a very bad idea. Just leave the -xi- prefix out.

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


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

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