The following is a sample of 10 lifetimes: 4 4 5+ 5+ 5+ 8 10+ 10* 12 15 where + indicates that a lifetime is right-censored. Determine the Nelson-Aalen estimate of /(11) and the Klein's approximation to the estimated variance of the Nelson-Aalen estimate of H(1 1). Using the Nelson-Aalen estimate of H(11) in the previous question, determine an estimate of S(11) and also compute the standard error of the estimate. Compare the two values with the estimates computed based on the Kaplan-Meier estimator and Greenwood's approximation of variance