You want to use coxme, currently found in the kinship package. It uses lme
style input, e.g.
coxme(Surv(time, status) ~ age + weight, data=mydata,
random= ~1 | school/teacher)
One note: your message seems to imply that you want to use group/subject as
the random effect. A Cox model with one random effect per subject is not
stable
-- actually an one where df(random effect) approaches the number of events is
not --- and you will likely get a variance estimate whose confidence interval
is
(0, huge number).
Terry Therneau
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