Chapter 11.2, Problem 13E

Treating circulatory disease: Angioplasty is a medical procedure in which an obstructed blood is widened. In some cases, a wire mesh tube, called a stent, is placed in the vessel to help it remain open. A study was conducted to compare the effectiveness of a bare metal stent with one that has been coated with a drug designed to prevent reblocking of the vessel. A total of 5320 patients received bare metal stents, and of these, 841 needed treatment for reblocking within a year. A total of 1120 received drug-coated stents, and 134 of them required treatment within a year. Can you conclude that the proportion of patients who needed retreatment is less for those who received drug-coated stents? Use the $\alpha =0.05$ level.