How to quit smoking It’s hard for smokers to quit.

Perhaps prescribing a drug to fight depression will work as well as the usual nicotine patch. Perhaps combining the patch and the drug will work better than either treatment alone. Here are data from a randomized, double-blind trial that compared four treatments.19 A

“success” means that the subject did not smoke for a year following the beginning of the study.

Group Treatment Subjects Successes 1 Nicotine patch 244 40 2 Drug 244 74 3 Patch plus drug 245 87 4 Placebo 160 25

(a) Summarize these data in a two-way table. Then compare the success rates for the four treatments.

(b) Explain in words what the null hypothesis H0: p1 =

p2 = p3 = p4 says about subjects’ smoking habits.

(c) Do the data provide convincing evidence of a difference in the effectiveness of the four treatments at the a = 0.05 significance level?