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\name{survSplit}
\alias{survSplit}
%- Also NEED an `\alias' for EACH other topic documented here.
\title{Split a survival data set at specified times }
\description{
Given a survival data set and a set of specified cut times, split
each record into multiple subrecords at each cut time. The new data
set will be in `counting process' format, with a start time, stop
time, and event status for each record.
}
\usage{
survSplit(data, cut, end, event, start, id = NULL, zero = 0,
episode=NULL)
}
%- maybe also `usage' for other objects documented here.
\arguments{
\item{data}{data frame}
\item{cut}{vector of timepoints to cut at}
\item{end}{character string with name of event time variable }
\item{event}{character string with name of censoring indicator }
\item{start}{character string with name of start time variable (will
be created if it does not exist) }
\item{id}{character string with name of new id variable to create (optional)}
\item{zero}{If \code{start} doesn't already exist, this is the time
that the original records start. May be a vector or single value.}
\item{episode}{character string with name of new episode variable (optional)}
}
\value{
New, longer, data frame.
}
\details{
The function also works when the original data are in
counting-process format, but the \code{id} and \code{episode} options
are of little use in this context.
}
\seealso{\code{\link{Surv}}, \code{\link{cut}}, \code{\link{reshape}} }
\examples{
aml3<-survSplit(aml,cut=c(5,10,50),end="time",start="start",
event="status",episode="i")
summary(aml)
summary(aml3)
coxph(Surv(time,status)~x,data=aml)
## the same
coxph(Surv(start,time,status)~x,data=aml3)
aml4<-survSplit(aml3,cut=20,end="time",start="start", event="status")
coxph(Surv(start,time,status)~x,data=aml4)
}
\Keyword{survival }% at least one, from doc/KEYWORDS
\keyword{utilities}% __ONLY ONE__ keyword per line
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