GERALD VAN BELLE is a professor in the Departments of Biostatistics and Environmental and Occupational Health Sciences at the University ofWashington in Seattle, Washington. He is the author of four books as well as more than 100 articles and numerous book chapters. LLOYD D. FISHER is Professor Emeritus in the Department of Biostatistics at the University of Washington, Seattle, and a consultant to the drug and device industries. He has held positions with the Center for AIDS Research, the Mayo Clinic, and the Fred Hutchinson Cancer Center, among others. PATRICK J. HEAGERTY is an ass...