In 2007, the FDA announced that the popular drug Zelnorm used to treat irritable bowel syndrome was withdrawn from the market, citing concerns about serious side effects. The analysis of several studies revealed that 13 of 11,614 patients receiving the drug had a serious side effect such as heart attack or stroke, compared to just 1 out of 7,031 on placebo.
a. Construct a 2 × 2 contingency table from these data.
b. Compute the relative risk and interpret.
c. Compute the odds ratio and interpret.
d. In a letter to health care professionals, the drug maker quoted a P-value of 0.024 for the comparison between the probability of a serious side effect in the drug and placebo group. By entering the data into the Fisher’s Exact Test web app (or other software), show that this is the P-value for Fisher’s exact test with a two-sided alternative hypothesis. What are the conclusions at a 0.05 significance level?