1. Department of Mathematics and Statistics McGill University Montreal Quebec Canada
2. Biostatistics Branch, Biometrics Research Program Division of Cancer Treatment and Diagnosis National Cancer Institute National Institutes of Health Bethesda MD USA
3. School of Public Health, Division of Biostatistics University of Minnesota Minneapolis MN USA
4. Department of Epidemiology, Biostatistics and Occupational Health McGill University Montreal Quebec Canada
5. Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics National Cancer Institute National Institutes of Health Bethesda MD USA