[R] Help in Coxme

Nelson Martins nelson.e.v.martins at gmail.com
Sun Jan 16 11:07:30 CET 2011

I am a relative newbie to survival analysis and R in general, but
would like to use the coxme package to analyse some data I currently
The data is relative to survival times of drosophila melanogaster
populations to infection with pathogens, and has the variables:
Treatment (4 treatments + 2 controls)
 and I'm currently using the following call
mixed<- coxme(formula = Surv(Time, Status) ~ strata(Treatment) + (1 |

The treatments have very different mortality profiles, that's why I'm
using stratification.
I have several problems:
1 - I'm able to get the results, and to compare the different treatments
using glht (e.g. - glht(mixed,mcp(Treatment="Tukey"))), only if I
don't stratify the treatments
2 - I'm  unable to plot the results as in other cox models (cph,coxph)
using survplot/survfit. The other models don't allow specifying random
variables (Populations and Replicates), which is of great importance
to me.
3 - One other problem I'm having is in plotting the hazard curves
(i.e. the instantaneous risk at each day). Is it possible to do it
these functions, hopefully with the associated standard errors?

Thank you for your time and help

Best regards
Nelson Martins

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