1. From the Department of Radiology and Biomedical Imaging, Yale School of Medicine, 333 Cedar St, Tompkins East 2-204, New Haven, CT 06520 (H.P.F., M.A.D.); Yale School of Management, New Haven, Conn (H.P.F.); Yale School of Public Health, New Haven, Conn (H.P.F.); and Economics Department, Yale University, New Haven, Conn (H.P.F.).