For each of the following research studies, explain why it is or is not an example of the experimental research strategy.

a. In a study examining the relationship between dietary fiber and cholesterol, a sample of 50-year-old men is randomly separated into two groups. Each group eats exactly the same diet for 2 months, except that one group also gets 2 cups of oatmeal every day. At the end of 2 months, the cholesterol level is measured for each man. The researcher hopes to find a difference between the two groups.

b. To evaluate the relationship between stress and general health, a researcher selects a random sample of 50-year-old men. For 2 months, each man is asked to keep a daily journal recording stressful events (such as a fight with his wife, an argument with his boss, or an automobile accident). After 2 months, a doctor examines each man and records an overall health rating. The goal of the study is to determine whether there is a relationship between the total amount of stress and overall health of the men.

c. In a study examining the relationship between self-esteem and dishonest behavior, college students were first given a self-esteem questionnaire to classify them into high and low self-esteem groups. At a later time, cheating behavior was measured while the students corrected their own exams. The goal of the study is to find a difference between the two groups.