Balancing Treatment Comparisons in Longitudinal Studies.

Sue M. Marcus, PhD, is with the Department of Psychiatry, Mount Sinai School of Medicine, New York. Juned Siddique, DrPH, is with the Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago. Thomas R. Ten Have, PhD, is with the Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia. Robert D. Gibbons, PhD, is Professor of Biostatistics and Psychiatry, and is Director of the Center for Health Statistics, University of Illinois at Chicago. Elizabeth Stuart, PhD, is with the Johns Hopkins Bloomberg School of Public Health, Baltimore. Sharon-Lise T. Normand, PhD, is with the Department of Health Care Policy, Harvard Medical School, and the Department of Biostatistics, Harvard School of Public Health, Boston. Address correspondence to Sue Marcus, PhD, Department of Psychiatry, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1230, New York, NY 10029; fax 212-8604630; or e-mail [email protected]. Dr. Marcus, Dr. Siddique, Dr. Ten Have, Dr. Gibbons, Dr. Stuart, and Dr. Normand, have disclosed no relevant fi nancial relationships. © 2 00 8/ Im ag ez oo /S to ck Il lu st ra tio n RF /G et ty Im ag es