We also express gratitude to the following individuals: Andrew Baum, Ph.D. (University of Pittsburgh Cancer Institute), Ronald C. Kessler, Ph.D. (Department of Health Care Policy, Harvard Medical School), David H. Marlowe, Ph.D. (Walter Reed Army Institute for Research, retired), Herbert Weiner, M.D. (School of Medicine, University of California, Los Angeles), and Kenneth B. Wells, M.D. (RAND). We thank David Persselin and Alan Shafer for their assistance in compiling data.