# cluster

0th

Percentile

##### Identify Clusters

This is a special function used in the context of the Cox model. It identifies correlated groups of observations, and is used on the right hand side of a formula.

Keywords
survival
##### Usage
cluster(x)
##### Arguments
x
A character, factor, or numeric variable.
##### Details

The function's only action is semantic, to mark a variable as the cluster indicator.

##### Value

• x

coxph, Surv
coxph(Surv(futime, fustat) ~ age + cluster(group), data = ovarian)