Refer to Original Source 9 on the companion website, “Suicide Rates in Clinical Trials of SS-RIs, Other Antidepressants, and Placebo: Analysis of FDA Reports.” Table 1 in that paper (page 791) provides confidence intervals for suicide rates for patients taking three different kinds of medications. For example, the 95% confidence interval for “Placebo” is 0.01 to 0.19. This interval means that we can be 95% confident that between 0.01% and 0.19% of the population of people similar to the ones in these studies would commit suicide while taking a placebo. Notice that 0.01% is about 1 out of 10,000 people and 0.19% is about 1 out of 526 people, so this is a wide interval in terms of the actual suicide rate. Also note that the population from which the samples were drawn consisted of depressed patients who sought medical help.
a. Report (from Table 1 in the article) the 95% confidence interval for the suicide rate for patients taking “selective serotonin reuptake inhibitors” (SSRIs). Write a sentence interpreting this interval.
b. Compare the interval for patients taking placebos with the one of those taking SSRIs. What can you conclude about the effectiveness of SSRIs in pre venting suicide, based on a comparison between the two intervals?
c. Read the article to determine whether the results are based on observational studies or randomized experiments. Based on that determination, can you conclude that differences that might have been observed in suicide rates for the different groups were caused by the difference in type of drug treatment? Explain.