1. Sixteen patients with advanced stomach carcinoma were randomized to receive one of two chemotherapies (Group A or Group B). The survival times from treatment (in weeks) are (+denotes a censored observation):

Group A: 63+, 59+, 57+, 40, 37, 33, 21+, 11 Group B: 57+, 51+, 44+, 32, 27, 27+, 10+, 6 (a) List two reasons an observation might be censored in this example.

(b) Construct survival curves.

(c) Does it appear that the individuals in one group have a longer time of survival than those in the other group? Explain your reasoning.

(d) Test the null hypothesis that the distributions are identical in the two treatment groups. What do you conclude? Include the results of your analysis.