anemia <- read.table("http://myweb.uiowa.edu/pbreheny/161/data/anemia.txt", header = T)
attach(anemia)



require(survival)
S <- Surv(Time,Status!=0)
fit <- survfit(S~1)
plot(fit, ylab = "Probability", xlab = "Time")



survdiff(S~Trt)
fit <- survfit(S~Trt)
plot(fit, ylab = "Probability", xlab = "Time")



plot(fit,mark.time=FALSE,col=c("gray","slateblue"),lwd=3,
     xlab="Time on study (Days)",ylab="Probability of survival")
text(900,.4,"MTX", col = "gray")
text(900,.9,"MTX+CSP", col = "slateblue")



S <- Surv(Time_gvhd,Status_gvhd)
survdiff(S~Trt)
fit <- survfit(S~Trt)
plot(fit) ## or survplot(fit)