1. Division of Epidemiology, Mayo Clinic College of Medicine, Rochester, Minnesota
2. Division of Biostatistics, Mayo Clinic College of Medicine, Rochester, Minnesota
3. Department of Health Sciences Research, and Department of Urology, Mayo Clinic College of Medicine, Rochester, Minnesota
4. Department of Epidemiology, Merck Research Laboratories, Blue Bell, Pennsylvania
5. Department of Research and Evaluation, Southern California Permanente Medical Group, Pasadena, California