[R] sbrier (Brier score) and coxph

[Stephen Henderson]

Hello
I've decided to try and distill an earlier rather ill focused question to
try and elicit a response. Any help is greatly appreciated. Why does mod.cox
not work with sbrier whilst mod.km does? Can I make it work?



> data(DLBCL)
> DLBCL.surv<-Surv(DLBCL$time,DLBCL$cens)
> 
> mod.km<-survfit(DLBCL.surv)
> mod.cox<-survfit(coxph(DLBCL.surv~IPI, data=DLBCL))
> 
> 
> sbrier(DLBCL.surv, mod.km)
integrated Brier score 
             0.2076454 
attr(,"time")
[1]   1.3 129.9
> sbrier(DLBCL.surv, mod.cox)
Error in switch(ptype, survfit = { : switch: EXPR must return a length 1
vector

Thanks in advance
Stephen Henderson



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