1. Department of Epidemiology and Department of Statistics, University of California, Los Angeles, Los Angeles, CA;
2. Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, Bethesda, MD;
3. Biometric Research Program, National Cancer Institute, Rockville, MD;
4. Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden;
5. Department of Epidemiology and Department of Biostatistics, Harvard T. Chan School of Public Health, Boston, MA