I would like to express my gratitude to the following individual reviewers for their insightful comments on earlier drafts: Robert J. Joy, M.D. (Uniformed Services University of the Health Sciences), Arieh Y. Shaleve, M.D. (Hadassah University Hospital), Harry Holloway, M.D. (Uniformed Services University of the Health Sciences), Grant Marshall, Ph.D. (RAND), and Harold Alan Pincus, M.D. (University of Pittsburgh Medical School and RAND).