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Identify clusters

Usage

cluster(x)

Arguments

x A character, factor, or numeric variable.

Description

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.

Value

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

See Also

coxph

Examples

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