A study was conducted to evaluate the relative efficacy of supplementation with calcium versus calcitriol in the treatment of postmenopausal osteoporosis. Calcitriol is an agent that has the ability to increase gastrointestinal absorption of calcium. A number of patients withdrew from this study prematurely due to the adverse effects of treatment, which include thirst, skin problems and neurologic symptoms. The relevant data appear below.
Yes No
Calcitriol 27 287
Calcium 20 288
a. Compute the sample proportion of subjects who withdrew from the study in each treatment group
b. Test the null hypothesis that there is no association between treatment group and withdrawal from the study at the 0.05 level of significance. What do you conclude?