(a) For the study in Exercise 4.139, use StatKey or other technology to create a randomization distribution for these data. Use the distribution to calculate a p-value. Interpret the results.

(b) In Example 4.29 on page 268, we saw that the p-value was 0.36 for testing whether lithium is better than a placebo in battling cocaine addiction. Using this p-value and your result from part (a), which drug shows stronger evidence that it is better than a placebo? Explain.

Exercise 4.139

In this exercise, we see that it is possible to use counts instead of proportions in testing a categorical variable. Data 4.7 describes an experiment to investigate the effectiveness of the two drugs desipramine and lithium in the treatment of cocaine addiction. The results of the study are summarized in Table 4.9 on page 267. The comparison of lithium to the placebo is the subject of Example 4.29. In this exercise, we test the success of desipramine against a placebo using a different statistic than that used in Example 4.29. Let p_d and p_c be the proportion of patients who relapse in the desipramine group and the control group, respectively. We are testing whether desipramine has a lower relapse rate than a placebo.