R help - Dec 2011 - What's the baseline model when using coxph with factor variables?

Hi all,

I'm trying to fit a Cox regression model with two factor variables but 
have some problems with the interpretation of the results. Considering 
the following model, where var1 and var2 can assume value 0 and 1:

coxph(Surv(time, cens) ~ factor(var1) * factor(var2),  data=temp)

What is the baseline model? Is that considering the whole population or 
the case when both var1 and var2 = 0?

Kind regards,
andi

On Dec 1, 2011, at 12:00 PM, Andreas Schlicker wrote:
> Hi all,
>
> I'm trying to fit a Cox regression model with two factor variables  
> but have some problems with the interpretation of the results.  
> Considering the following model, where var1 and var2 can assume  
> value 0 and 1:
>
> coxph(Surv(time, cens) ~ factor(var1) * factor(var2),  data=temp)
>
> What is the baseline model? Is that considering the whole population  
> or the case when both var1 and var2 = 0?
This has been discussed several times in the past on rhelp. My  
suggestion would be to search your favorite rhelp archive using   
"baseline hazard Therneau", since Terry Therneau is the author of  
survival. (The answer is closer to the first than to the second.)
>
> Kind regards,
> andi
>
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