############################################################
## Name: Joshua M. Tebbs
## Date: 22 Nov 2007
## Purpose: Simulation exercise. Example 4.6.
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## generate the data: n=50, failure mean = 5, censoring mean = 10
survtime <- rexp(50,0.2)
censtime <- rexp(50,0.1)

## creates indicator variable (Delta), 1, if surv < cens; 0, otherwise
status <- (survtime <= censtime)
## obstime are the observed (simulated) data we would see
obstime <- survtime*status + censtime*(1-status)

## Compute KM estimator
fit <- survfit(Surv(obstime,status), conf.type = "plain")
summary(fit)
plot(fit,xlab="Patient time (in years)", ylab="survival probability")
abline(h=0.5, lty=1)