1. Departments of Emergency Medicine (K.S.Z.), Massachusetts General Hospital, Boston.
2. Harvard Medical School (K.S.Z., L.H.S.), Boston, MA.
3. Social Networks Lab of the Department of Humanities, Social, and Political Sciences, ETH Zurich, Switzerland (V.A.).
4. Neurology (L.H.S., Z.Y.), Massachusetts General Hospital, Boston.
5. Massachusetts Department of Public Health, Boston, MA (V.N., A.C.).
6. Department of Epidemiology and Biostatistics of Michigan State University, East Lansing (M.J.R.).
7. Hankamer School of Business at Baylor University, Waco, TX (J.P.S.).
8. Faculty of Economics of the University of Italian Switzerland, Lugano, Switzerland (A.L.).
9. Department of Biostatistics at the Harvard T.H. Chan School of Public Health, Boston, MA (J.P.O.).