In an opinion column in the Washington Post, Daniel Morgan of the University of Maryland’s School of Medicine described the result of a study he carried out with colleagues: “We found that nearly 90 percent of the patients received at least one unnecessary [medical] test and that, overall, nearly one-third of all the tests were superfluous.” Why would hospitals and doctors perform tests that may not be of any value to patients? Are there features of the U.S. health care system that might be encouraging this behavior? Briefly explain.