cluster {survival} | R Documentation |
This is a special function used in the context of survival models. It
identifies correlated groups of observations, and is used on the right hand
side of a formula. Using cluster()
in a formula implies that
robust sandwich variance estimators are desired.
cluster(x)
x |
A character, factor, or numeric variable. |
x
data(kidney) frailty.model <- coxph(Surv(time, status)~ age + sex + disease + frailty(id), kidney) marginal.model <- coxph(Surv(time, status)~ age + sex + disease+cluster(id), kidney) summary(frailty.model) summary(marginal.model) data(rats) frailty.model <- survreg(Surv(time, status) ~ rx + frailty(litter), rats ) marginal.model <- survreg(Surv(time, status) ~ rx + cluster(litter), rats ) summary(frailty.model) summary(marginal.model)