survival (version 3.2-9)

aggregate.survfit: Average survival curves

Description

For a survfit object containing multiple curves, create average curves over a grouping.

Usage

# S3 method for survfit
aggregate(x, by = NULL, FUN = mean, ...)

Arguments

x

a survfit object which has a data dimension.

by

an optional list or vector of grouping elements, each as long as dim(x)['data'].

FUN

a function to compute the summary statistic of interest.

…

optional further arguments to FUN.

Value

a survfit object of lower dimension.

Details

The primary use of this is to take an average over multiple survival curves that were created from a modeling function. That is, a marginal estimate of the survival. It is primarily used to average over multiple predicted curves from a Cox model.

See Also

survfit

Examples

# NOT RUN {
cfit <- coxph(Surv(futime, death) ~ sex + age*hgb, data=mgus2)
# marginal effect of sex, after adjusting for the others
dummy <- rbind(mgus2, mgus2)
dummy$sex <- rep(c("F", "M"), each=nrow(mgus2)) # population data set
dummy <- na.omit(dummy)   # don't count missing hgb in our "population
csurv <- survfit(cfit, newdata=dummy)
dim(csurv)  # 2 * 1384 survival curves
csurv2 <- aggregate(csurv, dummy$sex)
# }