Cholesterol. A pharmaceutical company tested three formulations of cholesterol-lowering drugs for patients with very high levels of cholesterol, to determine whether any differences exist in their efficiency. For the experiment, 30 volunteers were selected and 10 were randomly assigned to one of three drug formulations. The subjects were instructed to take the drug during a 2-month period and the percentage reduction in cholesterol was recorded.

a) Use the Kruskal-Wallace test to judge whether there is a difference among the drugs.

b) What aspect of these data may make the Kruskal-Wallace test more appropriate for these data than the ANOVA methods of Chapter 20?