# This R source file is available at www.richardsconsulting.co.uk/lectures

# Load in the library of survival functions
library(survival)

# Create a vector of observation times
times<-c(10, 13, 18, 19, 23, 30, 36, 38, 54, 56, 59, 75, 93, 97, 104, 107, 107, 107)

# Create a vector of event types -- '1' for death, '0' for censored
events<-c(1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0)

#Take a look at the survival data -- '+' marks censored observation
Surv(times, events)

# Calculate the Kaplan-Meier survival estimates
kapmei<-survfit(Surv(times, events) ~ 1)

# Take a look at the estimates and confidence intervals
# Compare these results with the table on page 7 of the red book
summary(kapmei)

# Plot survival estimates
plot(kapmei, xlab="Time", ylab="Proportion surviving", main="Kaplan-Meier estimate of survival function", sub="Dash lines are confidence intervals, tickmarks are censored observations")