1. Surveillance Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, U.S.A.
2. Department of Mathematics, Syracuse University, Syracuse, New York, U.S.A.
3. Surveillance Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, U.S.A.; and Division of Cancer Registration and Surveillance, National Cancer Center, Korea