pdf("ex0903.pdf")

ex0903dat <- read.fwf("http://www.stat.ufl.edu/~winner/data/biostat/ex0903.dat", width=c(8,8,8,8,8), 
 col.names=c("pair", "remiss","group","remisstime","censor"))

ex0903 <- data.frame(ex0903dat)

attach(ex0903)

ex0903

# Load the survival analysis package  

library(survival)


# Obtain survival tables and curves by group

surv.byreg <- survfit(Surv(remisstime, censor==0)~group)

summary(surv.byreg)

plot(surv.byreg)

# Conduct the Log-Rank test to compare survival curves

survdiff(Surv(remisstime,censor==0)~group)

# Fit the Proportional Hazards Model

ex0903.cph <- coxph(Surv(remisstime,censor==0) ~ group)

summary(ex0903.cph)


dev.off()