R/KMW3df.R

In gsoutinho/survrec: Estimation of the multivariate distributions for censored gap times

#' Kaplan-Meier Weighted estimator for the general case of K gap times distribution function.
#' 
#' @description Provides estimates for the general case of K gap times distribution function
#' based on Kaplan-Meier Weights: Kaplan-Meier Weighted estimator, KMW.
#' @usage KMW3df(object, x, y, z)
#' @param object An object of class multidf.
#' @param x The first time for obtaining estimates for the general case of distribution function.
#' @param y The second time for obtaining estimates for the general case of distribution function.
#' @param z The third time for obtaining estimates for the general case of distribution function.
#' @return Vector with the Kaplan-Meier Weighted estimates for the general case of K gapes times
#' distribution function.
#' @references 
#' de Una-Alvarez J, Meira Machado LF (2008). "A Simple Estimator of the Bivariate Distribution
#' Function for Censored Gap Times", Statistical and Probability Letters, 78, 2440-2445.
#' Davison, A.C. and Hinkley, D.V. (1997) "Bootstrap Methods and Their Application", Chapter 5.
#' Cambridge University Press.
#' @seealso \code{\link{LDM3df}}, \code{\link{LIN3df}} and \code{\link{WCH3df}}.
#' 
#' @examples
#' b4state <- multidf(time1=bladder5state$y1, event1=bladder5state$d1,
#' time2= bladder5state$y1+bladder5state$y2, event2=bladder5state$d2,
#' time=bladder5state$y1+bladder5state$y2+bladder5state$y3, status=bladder5state$d3)
#' head(b4state)[[1]]
#' 
#' KMW3df(b4state,x=13,y=20,z=40)
#' 
#' b4 <- multidf(time1=bladder4$t1, event1=bladder4$d1,
#'              time2= bladder4$t2, event2=bladder4$d2,
#'              time=bladder4$t3, status=bladder4$d3)

#' KMW3df(b4,x=13,y=20,z=40)
#'
#' @author Gustavo Soutinho and Luis Meira-Machado


KMW3df <-
function(object, x, y, z)
{
 obj <- object[[1]]
 est <- 0
 G <- KMW(obj$time, obj$status)
      p <- which(obj$time1 <= x & obj$time - obj$time1 <= y, obj$time - obj$time2 <= z)
     est <- sum(G[p])
 return(est)                    
}