The tt function is documented for coxph, and you are using cph.   They are not 
the same.

On 09/03/2013 05:00 AM, r-help-requ...@r-project.org wrote:
tt<- function(x) {
                 obrien<- function(x) {
                   r<- rank(x)
                   (r - 0.5)/(0.5 + length(r) - r)
                 }
                 unlist(tapply(x, riskset, obrien))
             }
hi,  i am newer in R. when dealing  with a survival data, i have found the variable progression was 
not met the PH assumption.the picture show the residual agaist time.So i  use Cox model for 
time-depandent varibles.   i  use the default tt in function coxph,but when i use tt in 
"f<-cph(Surv(os$Stime,os$Status==1)~Metastasis+Surgery+Post.chem. +Age+tt(Progression)+ ALP, 
data=os, x=T, y=T, surv=TRUE, time.inc=60)",it didn't work. i don't kown what the 
arg"riskset" is .i beg your help . can you help me write down a appropriate tt expression to 
let me use in cph. thanks.
                                                                                
                                                                       Zhongxin 
Dong


______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Reply via email to