[R] Extracting parameters for Gamma Distribution

Thomas Lumley tlumley at u.washington.edu
Wed Nov 8 16:24:26 CET 2006

On Tue, 7 Nov 2006, yongchuan wrote:

> I'm doing a cox regression with frailty:
> model <- coxph(Surv(Start,Stop,Terminated)~ X + frailty(id),table)
> I understand that model$frail returns the group level frailty
> terms. Does this mean this is the average of the frailty
> values for the respective groups?

It is the frailty value that is common to all the measurements with the 
same id value.

> Also, if I'm fitting it to
> a gamma frailty, how do I extract the rate and scale
> parameters for the different gamma distributions fit to each
> group? Thanks.

There are not different gamma distribution fit to each group. There is one 
gamma distribution.


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