Dana P Goldman1, Geoffrey F Joyce2, William B Vogt3. 1. Norman Topping Chair in Medicine and Public Policy and Director, Leonard D. Schaeffer Center for Health Policy and Economics, University of Southern California, 650 Childs Way, RGL 214, Los Angeles, CA 90089-0626. 2. Joyce: School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90089-9121. 3. Vogt: Department of Economics, Terry College, University of Georgia, 513 Brooks Hall, Athens, GA 30602.