Six rats were exposed to carcinogens by injecting tumor cells into their feet. The times to develop a tumor of a given size were observed. The investigator decided to terminate the experiment after 30 weeks. Rats A, B, and D developed tumors after 10, 15, and 25 weeks, respectively. Rats C and E had not developed tumors by the end of the study. Rat F died accidentally without any tumors after 19 weeks of observation.
a. Describe the time-to-event random variable.
b. Which rats had complete event times?
c. Which rats had censored event times? What type of censoring occurred? Be as specific as possible.