prodlim (version 2025.04.28)

followup: Estimation of the median potential followup time.

Description

The reverse Kaplan-Meier method estimates the median potential followup time.

Usage

followup(formula, cens.code = 0, data, ...)

Value

The estimated median potential followup time with inter quartile ranges.

Arguments

formula

A formula whose left hand side is a Hist or a Surv object specifying the event time and the event type where by default 0=censored, 1=event, 2=competing risk (if any). Use cens.code to change the value for censored.

cens.code

Value of the event

data

A data.frame in which all the variables of formula can be interpreted.

...

Arguments passed to prodlim.quantile.

Author

Thomas A. Gerds <[e-mail]>

Details

This is merely a wrapper for prodlim with argument reverse.

References

Michael Schemper and Terry L. Smith. A note on quantifying follow-up in studies of failure time. Controlled Clinical Trials, 17(4):343--346, 1996.

See Also

prodlim

Examples

set.seed(8)
d <- SimCompRisk(117)

# overall
followup(Hist(time,event)~1,data=d)

# in strata defined by variable X1 
followup(Hist(time,event)~X1,data=d)