Re: [R] Coxph with factors

From: Kylie-Anne Richards <kar_at_itga.com.au>
Date: Sun 17 Jul 2005 - 21:27:45 EST

Thank you again for your help.

Your suggestions worked perfect. The problems I had when using f.pom=factor(-3, levels=seq(-3,2.5, by=0.5)) were a silly mistake on my part (as suspected and dually pointed out). Thanks for the notes on baseline. I was not aware of the inaccuracies when using it at z=0.

I will be back with questions on computationally efficient time dependant survival functions next month.

Cheers,
Kylie-Anne

> On Sat, 16 Jul 2005, Thomas Lumley wrote:
>>
>> Yes, but you don't need to go via the baseline. The survival curves for
>> any two covariate vectors z1 and z2 are related by
>>
>> S(t; z1)= S(t; z2)^(z1-z2)
>>
> Actually
> S(t; z1)=S(t;z2) ^(beta'(z1-z2))
>
> of course.
>
> -thomas
>



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