R/PKM.R

In sestelo/condsurv: Estimation of the Conditional Survival Function for Ordered Multivariate Failure Time Data

#' Presmoothed Kaplan-Meier product-limit estimate of survival.
#' 
#' This function provides survival estimates using the presmoothed
#' product-limit Kaplan-Meier estimator.
#' 
#' 
#' @param time Survival time of the process.
#' @param status Censoring indicator of the survival time of the process; 0 if
#' the survival time is censored and 1 otherwise.
#' @param t The time for obtaining survival estimates.
#' @author Luis Meira-Machado and Marta Sestelo
#' @seealso \code{\link{KM}}
#' @references R. Cao, I. Lopez-de Ullibarri, P. Janssen, and N. Veraverbeke.
#' Presmoothed kaplan-meier and nelsonaalen estimators. Journal of
#' Nonparametric Statistics, 17:31-56, 2005.
#' 
#' G. Dikta. On semiparametric random censorship models. Journal of Statistical
#' Planning and Inference, 66:253-279, 1998.
#' 
#' E. Kaplan and P. Meier. Nonparametric estimation from incomplete
#' observations. Journal of the American Statistical Association, 53:457-481,
#' 1958.
#' @examples
#' 
#' obj <- with(colonCS, survCS(time1, event1, Stime, event))
#' PKM(time = obj$Stime, status = obj$event, t = 1095)
#' 
PKM <-
function(time,status,t)
{
 if (missing(time)) stop("Argument 'time' is missing with no default")
 if (missing(status)) stop("Argument 'status' is missing with no default")
 if (missing(t)) stop("Argument 't' is missing with no default")
p <- which(time <= t)
res <- 1 - sum(PKMW(time,status)[p])
return(res)
}