Question

Thalidomide is a tranquilizer that was prescribed in the late 1950’s and early 1960’s to pregnant women, with the devastating result of over 12,000 birth defects in 48 countries before it was banned in 1962. (It was never sold in the United States.) Since then, the drug has reappeared as a possible solution to a number of medical problems. The U.S. National Institutes of Health announced on 31 October 1995 the results of a study in 30 hospitals of the effectiveness of thalidomide in healing mouth ulcers in AIDS patients. In the study, which was chaired by Dr. Jeffrey Jacobson of the Bronx Veteran Affairs Medical Center and the Mount Sinai School of Medicine in New York, it was found that 14 out of 23 patients who received thalidomide had their ulcers heal compared to 1 out of 22 patients who received a placebo. As a result of these early trial outcomes, the researchers suspended the trial giving thalidomide to all the patients in the study. (Sec. 8.2)

1. Find a 90% confidence interval for the difference in proportion of healing assuming that both samples are simple random samples and independent of each other.
2. Conduct the appropriate large-sample test of significance. Discuss your results and compare your conclusion with the decision of the researchers.

Answer 1

p^ = X/n

(p1^ - p2^) +- z* sqrt(p1^(1-p1^)/n1 + p2^(1-p2^)/n2)

=(0.381,0.746)