Dear all, I have been doing some frailty calculations and been facing some difficulties. I can extract coefficients, value of theta and the following things library(survival) fit<-coxph(Surv(time,status)~covariate+frailty(group), data=simulated.data) fit$coef fit$history[[1]]$theta fit$history[[1]]$c.loglik fit$var fit$var2 from a frailty included coxph object: but how can i know what other possible things that i can extract from the same object "fit"? Also, i cannot use var2 (defined on page 122) as a function as Therneau, Grembsch (2000) page 249 implemented in apply(), unlike var: why is that? Do i need to define it first, or, the function is not for R? Again, is there any already written complete program in R for estimating frailty models with nested effects (at leat 2 stage)? Thanks for you time: Thanks in advance: hope some one may help me with the above quaries. Mohammad Ehsanul Karim Institute of Statistical Research and Training University of Dhaka [[alternative HTML version deleted]]