Clinical Tests of Viagra In clinical tests of adverse reactions to the drug Viagra, 4.0%

of the 734 subjects in the treatment group experienced nasal congestion, but 2.1% of the 725 subjects in the placebo group experienced nasal congestion (based on data from Pfizer Pharmaceuticals).

a. Construct a 95% confidence interval estimate of the proportion of Viagra users who experience nasal congestion.

b. Construct a 95% confidence interval estimate of the proportion of placebo users who experience nasal congestion.

c. Construct a 95% confidence interval estimate of the difference between the two population proportions.

d. When attempting to determine whether there is a significant difference between the two population proportions, which of the following methods is best?

i. Determine whether the confidence intervals in parts

(a) and

(b) overlap.

ii. Determine whether the confidence interval in part

(c) contains the value of zero.

iii. Conduct a hypothesis test of the null hypothesis p1 5 p2, using a 0.05 significance level.

iv. The methods in parts (i), (ii), and (iii) are all equally good.