aggregate.survfit {survival} | R Documentation |
For a survfit object containing multiple curves, create average curves over a grouping.
## S3 method for class 'survfit'
aggregate(x, by = NULL, FUN = mean, ...)
x |
a |
by |
an optional list or vector of grouping elements, each as
long as |
FUN |
a function to compute the summary statistic of interest. |
... |
optional further arguments to FUN. |
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.
a survfit
object of lower dimension.
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)