1. From the Departments of Epidemiology (W.G.P., S.Y.J., N.S.C., H.E., D.S.B.) and Biostatistics (J.G., A.C., S.B.), Graduate School of Public Health, the Department of Medicine, School of Medicine (B.Y.L.), and the Graduate Information Science and Technology Program, School of Information Sciences (V.Z.), University of Pittsburgh, Pittsburgh; and the Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore (D.C.).