Studies are often done by pharmaceutical companies to determine the effectiveness of a treatment program. Suppose that a new AIDS antibody drug is currently under study. It is given to patients once the AIDS symptoms have revealed themselves. Of interest is the average length of time in months patients live once starting the treatment. Two researchers each follow a different set of 50 AIDS patients from the start of treatment until their deaths.

c. Can you tell if one researcher is correct and the other one is incorrect? Why?

d. Would you expect the data that a specific researcher is collecting to be identical? Why or why not?