[R] Nested frailty model

Dear R-help, I am trying to estimate a Cox model with nested effects, or better h(t,v,w)=v*w*h0(t)*exp(B'x) where h(t,v,w) is the individual hazard function w and v are both frailty terms (gamma or normal distributed) I have 12 clusters and for each one of them I would like to associate a

[R] Correlated frailty model

Dear R-help, I am trying to a estimate a correlated frailty model. My dataset is made up of 4 observations. I would like to know if it is too big or I have done some mistakes in the following code. group<-paste(usa$id,usa$mob) mixed.logn<-coxme(Surv(yearspan)~ south+mod, data=usa,random= ~ 1

[R] enquiry

Dear R-help, I am trying to estimate a Cox model with nested effects basing on the minimization of the overall AIC; I have two frailties terms, both gamma distributed. There is a error message (theta2 argument misses) and I don?t understand why. I would like to know what I have wrong. Thank y