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therneau
2011 Jul 10
1
Package "survival" --- Difference of coxph strata with subset?
[code]>require("survival")
> coxph(Surv(futime,fustat)~age + strata(rx),ovarian)
Call:
coxph(formula = Surv(futime, fustat) ~ age + strata(rx), data = ovarian)
coef exp(coef) se(coef) z p
age 0.137 1.15 0.0474 2.9 0.0038
Likelihood ratio test=12.7 on 1 df, p=0.000368 n= 26, number of events= 12
> coxph(Surv(futime,fustat)~age, ovarian, subset=rx==1)
2010 May 22
0
Modeling time varying effects in with cph: how to ?
...u/R/Rhelp02/archive/52828.html
It seems that SAS is more well-suited to this purpose, as explained
in the links above, but i do not have enough time to learn SAS.
I think i should use something like this:
cph(Surv(start,end,status)~a.factor+a.factor:start)
but i'm not sure, specially after Thernau's reply to my previous post.
Assuming i'm doing well, i'd prefer to use cph because of the
rms bootstrap validation facilities.
Unfortunately cph doesn't wanto to model an interaction term without
the both corresponding main effects:
> fit.cph <- cph(TACE.Surv~PS+PS:TIME.s...