A Quaker Oatmeal box reported the following: "100 people in Lafayette, Colorado volunteered to eat a good-sized bowl of oatmeal for 30 days to see if simple lifestyle changes-like eating oatmeal-could help reduce cholesterol. After 30 days, 98 lowered their cholesterol. With these great results, the people in Lafayette proved to themselves that simple changes can make a real difference."37

a. Was this an observational study or an experiment?

b. There are two variables of interest. What was the explanatory variable?

c. Was the explanatory variable categorical or quantitative?

d. What was the response variable?

e. Was the response variable categorical or quantitative?

f. Describe the treatment group.

g. Was there a randomized assignment to treatment or control? Explain.

h. Describe other possible reasons, besides eating oatmeal, that could account for the participants' cholesterol being lowered.

i. Which one of these is more problematic here: experimenter effect or Hawthorne effect?

j. Would Quaker Oats' results have been more convincing if it had used 1,000 instead of 100 volunteers?

k. Describe details of a study design that might be more effective than this one in establishing whether or not oatmeal lowers cholesterol.