# R: Survival Curve Object

survfit.object {survival} | R Documentation

## Survival Curve Object

### Description

This class of objects is returned by the `survfit` class of functions to represent a fitted survival curve.

Objects of this class have methods for the functions `print`, `summary`, `plot`, `points` and `lines`. The `print.survfit` method does more computation than is typical for a print method and is documented on a separate page.

### COMPONENTS

The following components must be included in a legitimate `survfit` object.

time
  the time points at which the curve has a step.
n.risk
  the number of subjects at risk at t.
n.event
  the number of events that occur at time t.
surv
  the estimate of survival at time t+0. This may be a vector or a matrix.
strata
  if there are multiple curves, this component gives the number of elements of the `time` etc. vectors corresponding to the first curve, the second curve, and so on. The names of the elements are labels for the curves.
std.err
  the standard error of the cumulative hazard or -log(survival).
upper
  upper confidence limit for the survival curve.
lower
  lower confidence limit for the survival curve.
conf.type
  the approximation used to compute the confidence limits.
conf.int
  the level of the confidence limits, e.g. 90 or 95%.
na.action
  the returned value from the na.action function, if any. It will be used in the printout of the curve, e.g., the number of observations deleted due to missing values.
call
  the call that produced the object.

### SUBSCRIPTS

Survfit objects that contain multiple survival curves can be subscripted. This is most often used to plot a subset of the curves. Usually a single subscript will be used. In one particular case – survival curves for multiple covariate values, from a Cox model that includes a `strata` statement – there is a matrix of curves and 2 subscripts may be used. (In this case `summary.survfit` will also print the data as a matrix).

### See Also

`survfit`, `plot.survfit`, `summary.survfit`, `print.survfit`.

[Package survival version 2.32 Index]