[R] Kaplan Meier Post Hoc?

Terry Therneau therneau at mayo.edu
Thu Oct 25 13:50:30 CEST 2012

No, you didn't miss anything in the survival package.  I've never found post-hoc tests 
interesting so have little motivation to add such (and a very long "to do" list of things 
I would like to add).

If you simply must have them, why not do all pairwise tests?

chisq <- matrix(0., 4,4)
for (i in 1:4) {
     for (j in (1:4)[-i]) {
          temp <- survdiff(Surv(time, status) ~ group, data=mydata,
                              subset=(group %in% (unique(group))[c(i,j)]))
          chisq[i,j] <- temp$chisq

Terry Therneau

On 10/25/2012 05:00 AM, r-help-request at r-project.org wrote:
> This is more of a general question without data.  After doing 'survdiff',
> from the 'survival' package, on strata including four groups (so 4 curves
> on a Kaplan Meier curve) you get a chi squared p-value whether to reject
> the null hypothesis or not.  Is there a method to followup with pairwise
> testing on the respective groups?  I have searched the library but have
> come up with nothing.  Perhaps I am mistaken in something here.

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