Osteoporosis is a condition in which people experience decreased bone mass and an increase in the risk of bone fracture. Actonel is a drug that helps combat osteoporosis in postmenopausal women. In clinical trials, 1374 postmenopausal women were randomly divided into experimental and control groups. The subjects in the experimental group were administered 5 milligrams (mg) of Actonel, while the subjects in the control group were administered a placebo. The number of women who experienced a bone fracture over the course of 1 year was recorded. Of the 696 women in the experimental group, 27 experienced a fracture during the course of the year. Of the 678 women in the control group, 49 experienced a fracture during the course of the year.

(a) Test the hypothesis that a lower proportion of women in the experimental group experienced a bone fracture than the women in the control group at the α = 0.01 level of

significance.

(b) Construct a 95% confidence interval for the difference between the two population proportions, pexp - pcontrol.

(c) What type of experimental design is this? What are the treatments?

(d) The experiment was double-blind. What does this mean?