Using the information in Table 9.7, answer the following: 

a. Compute the standard error for the estimate of the probability that a patient receiving maintenance chemotherapy will relapse after 15 weeks. 

b. Compute and interpret a 95% confidence interval [based on Equation (9.8)] for the probability that a patient receiving maintenance chemotherapy will relapse after 15 weeks. The critical value is 1.96. 

c. Suppose a doctor claims that fewer than 50% of patients receiving maintenance chemotherapy will relapse after 15 weeks. Based on your answer to Part B, how would you respond to this claim?

Figure 9.18 Kaplan-Meier curves for AML relapse times for patients who did and did not receive maintenance chemotherapy.

Table 9.7 Quantities associated with patients with AML who received maintenance chemotherapy.

Survival Plot for Time Kaplan-Meler Method Censoring Column in Status 1.0 Group Mainkenance Chemo No Maintenance Chem 0.8 2 061 0.4 0.2 0.0 0 20 4060 80 100 120 140 160 180 Time from Randomization(Weeks) 0 [0,9) 00 19, 13 91 2 | [13, 18) | 13 | 10 | 3 [18, 23 8 81 4[23, 31 23 71 5 [31, 34)3 5 1 6 [34, 48) 34 41 7[48, 161)| 4821 2