In Reply Efficient health care requires informed physicians and patients, as Yeh rightly notes. Our health care system falls short on both counts. To illustrate the extent of the problem, consider cancer screening. In a representative sample of some 5000 women in 9 European countries, 92% overestimated the reduction of breast cancer mortality by mammography by a factor of 10 to 200, or they did not know. For men and PSA screening, this number was 89%.1 If it were not for the Russians, who had the most realistic estimates among the Europeans, these numbers would be even closer to 100%. Among 160 German gynecologists, 80% did not understand the positive predictive value of a positive mammogram, with estimates varying between 1% and 90%.2 Among a national sample of 412 US primary care physicians, 47% wrongly thought that if more cancers are detected by a screening test, this proves that the test saves lives, and 76% mistakenly believed that if screen-detected cancers have better 5-year-survival rates than cancers detected by symptoms, this would prove that a screening test saves lives.3