Kaplan-Meier and Nelson-Aalen estimates with and without survfit function from survival package

Data reading:


rm(list=ls(all=TRUE)) # wipe out everything else
require(survival)
data = aml[aml$x == "Maintained",]
data

Comparing Risks

To evaluate whether an exposure is at all contributing to risk of disease, the simplest form of comparison is as follows:
x1 ~ Binomial(n1, pi1)
x2 ~ Binomial(n2, pi2)