GPH-GU 2368: Applied Survival Analysis

Homework 4

Problem 4

Listed below are values of survival time (length of follow-ups) years for 6 males and 6 females

from the WHAS study. Right-censored times are denoted by a "+" as a superscript.

Males: 1, 3, 4+, 10, 12, 18

Females: 1, 3+, 6, 10, 11, 12

Compute by hand, and verify hand calculations with a software package, the log-rank, generalized Wilcoxon, and Peto-Prentice tests for the equality of the two survival functions estimated before.

Problem 6

Repeat problem 1 using the WHAS500 data with four groups defined by the age intervals:

[40-5]|, [60, 69], [70, 79] and [80,90].

Log-rank test

sv <- survdiff(Surv(lenfol, fstat) ~ gender + age_group, data = whas500) sv

survdiff(formula = Surv(lenfol, fstat) ~ gender + age_group,

data = whas500)

n=468, 32 observations deleted due to missingness.

N Observed Expected (O-E)^2/E (O-E)^2/V

gender=0, age_group=1 95 10 46.1 28.26 37.41

gender=0, age_group=2 65 14 29.8 8.35 9.91

gender=0, age_group=3 64 34 25.2 3.10 3.57

gender=0, age_group=4 52 41 15.4 42.84 46.96

gender=1, age_group=1 33 9 17.6 4.22 5.32

gender=1, age_group=2 28 10 12.5 0.50 0.54

gender=1, age_group=3 57 30 24.6 1.18 1.36

gender=1, age_group=4 74 47 23.9 22.35 25.75

Chisq= 113 on 7 degrees of freedom, p= <2e-16

Generalized Wilcoxon test

PLease help me with the rest and show results from R studio please