intcox (version 0.9.1.1)

intcox.example: Example set for interval censored data with four covariates

Description

Weibull distributed survival times with four covariates interval censored by a fixed grid

Usage

data(intcox.example)

Details

The example dataset consists of 200 Weibull distributed random variables with shape=0.75, while scale is derived from $(1/\lambda)^(1/shape)$ with $\lambda = \exp{\beta_0+\beta'X}$ where $\beta = {0.5,-0.5,0.5,0.5}'$ and design matrix X which is formed by the four covariates. Furthermore, an interval was generated where the left interval end is zero and the right interval end is defined by maximum value (T.max) of the which is got by the 0.9-quantile of a Weibull r.v. with shape=0.75 and scale=median(scale). If the value of event time >=T.max then the event time is right censored (left=T.max and right=NA). Otherwise the interval [0,T.max] was randomly divided into subintervals (grid=10) in order to determine the corresponding interval ends for each event time which is not right censored. The generating code is given below.

Examples

sim.weibull.intcox.rfc <-function (N=200,beta.0=0.1,beta.cov=c(0.5,-0.5,0.5,0.5),alpha=0.75,p.cov=c(0.5,0.75),grid=10)
{																		
  x.design<-cbind(rbinom(N,1,p.cov[1]),rbinom(N,1,p.cov[2]),runif(N,-1,1),rnorm(N,0,1))
  colnames(x.design)<-paste("x.",1:4,sep="")
  lambda<-exp(beta.0+x.design%*%matrix(beta.cov,ncol=1))
  scale<-(1/lambda)^(1/alpha)
  t.true<-rweibull(N,alpha,scale)
  T.max<-max(qweibull(0.9,alpha,median(scale)))
  t.left<-NULL
  t.right<-NULL
  for (i in 1:N) {
      tt<-unique(c(0,sort(runif(grid,0,T.max)),T.max))
      if (t.true[i]>=T.max) {
          x.left<-T.max
          x.right<-NA
      } else {
          x.left<-max(tt[t.true[i]>tt])   
          x.right<-min(tt[t.true[i]<tt])
      }
      t.left<-c(t.left,x.left)
      t.right<-c(t.right,x.right)
  }
  return(data.frame(ID=1:N,left=t.left,right=t.right,x.design))
}

data(intcox.example)