Suppose that you want to determine whether the use of one aspirin per day for people age 50 and older reduces the chance of heart attack. You have 200 people available for the study: 100 men and 100 women. You suspect that aspirin might affect men and women differently.
To ensure an appropriate comparison group, those who do not get aspirin should get a placebo.
a. Identify the treatment and response variables.
b. Describe in detail a simple randomized design (not blocked) to test whether aspirin lowers the risk of heart attack.
c. Describe a blocked design to test whether aspirin lowers the risk of heart attack; the blocking variable is gender.
d. Explain why researchers might prefer a blocked design.