survexp.object: Expected Survival Curve Object
In survival: Survival Analysis

survexp.object

R Documentation

Expected Survival Curve Object

Description

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

Objects of this class have methods for summary, and inherit the print, plot, points and lines methods from survfit.

Arguments

`surv`	the estimate of survival at time t+0. This may be a vector or a matrix.
`n.risk`	the number of subjects who contribute at this time.
`time`	the time points at which the curve has a step.
`std.err`	the standard error of the cumulative hazard or -log(survival).
`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.
`method`	the estimation method used. One of "Ederer", "Hakulinen", or "conditional".
`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`	an image of the call that produced the object.

Structure

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

Subscripts

Survexp objects that contain multiple survival curves can be subscripted. This is most often used to plot a subset of the curves.

Details

In expected survival each subject from the data set is matched to a hypothetical person from the parent population, matched on the characteristics of the parent population. The number at risk printed here is the number of those hypothetical subject who are still part of the calculation. In particular, for the Ederer method all hypotheticals are retained for all time, so n.risk will be a constant.