Q1: The following data were derived from a study of survival time in months for two groups of leukemia patients, with 21 patients in each group. Group 1 is the treatment group, and Group 2 is the placebo group. The study question is whether the treatment improved survival compared with the placebo for leukemiapatients.

Data: survival time (months) for two groups of leukemia patients

Event: death

Group 1(treatment)	Group 2 (placebo)
6, 6, 6, 7, 10, 13, 16, 22, 23, 6+, 9+, 10+, 11+, 17+, 19+, 20+, 25+, 32+, 32+, 34+, 35+	1, 1, 2, 2, 3, 4, 4, 5, 5, 8, 8, 8, 8, 11, 11, 12, 12 15, 17, 22, 23

Note: + denotes censored

1. Calculate the Kaplan-Meier survival estimates for Group 1 and Group 2 using the following table (you can generate additional rows if needed)

Group 1

Time Interval

Number at risk (n)

Number of death (d)

Number of censored (c)

Conditional probability of survival (p)

Survival