Chapter 14, Problem 38E

Exercises 37 through 40 refer to a clinical study conducted at the Houston Veterans Administration Medical Centre on the effectiveness of knee surgery to cure degenerative arthritis (osteoarthritis) of the knee. Of the 324 individuals who met the inclusion criteria for the study, $144$ declined to participate. The researchers randomly divided the remaining $180$ subjects into three groups: One group received a type of arthroscopic knee surgery called debridement; a second group received a type of arthroscopic knee surgery called lavage; and a third group received skin incisions to make it look like they had had arthroscopic knee surgery, but no actual surgery was performed. The patients in the study did not know which group they were in and in particular did not know if they were receiving the real surgery or simulated surgery. All the patients who participated in the study were evaluated for two years after the procedure. In the two-year follow-up, all three groups said that they had slightly less pain and better knee movement, but the “fake” surgery group often reported the best results. [Source: New England Journal of Medicine, $347$, no. 2 (July 11, $2002$ ): $81–88$.]

a. Was the sample chosen by random sampling? Explain.

b. Was this study a controlled placebo experiment? Explain.

c. Describe the treatment group(s) in this study.