1. National Cancer Institute, Bethesda, MD, USA
2. Department of Epidemiology, Brown University School of Public Health, Providence, RI, USA
3. Center for Statistical Sciences, Brown University School of Public Health, Providence, RI, USA
4. Westat, Inc., Rockville, MD, USA
5. Drexel University School of Public Health, Philadelphia, PA, USA
6. Information Management Systems, Inc., Rockville, MD, USA
7. Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada