An advertisement for Seldane‐D, a drug prescribed for seasonal allergic rhinitis, reported results of a double‐blind study in which 378 patients took Seldane‐D and 196 took a placebo. Headaches were reported as
a side effect by 67 of those taking Seldane‐D.
(a) What is the sample proportion of Seldane‐D takers who reported headaches?
(b) What is the standard deviation for the proportion computed in part (a)?
(c) Construct a 98% confidence interval for the population proportion based on the information from parts (a)
and (b).
(d) Interpret the confidence interval from part (c) by writing a few sentences explaining what it means.
(e) Of the 196 placebo takers, 46 reported headaches. Compute a 98% confidence interval for the true
population proportion that would get headaches after taking a placebo.
(f) Notice that a higher proportion of placebo takers than Seldane‐D takers reported headaches. Use that information to explain why it is important to have a group taking placebos when studying the potential side
effects of medications.