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 2.20

Index]