Advanced Analytics Division, SAS Institute Inc., Cary, NC 27513, Molecular and Genetic Epidemiology Section, Epidemiology Branch and Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 and Department of Statistical Science, Duke University, Durham, NC 27708.|Advanced Analytics Division, SAS Institute Inc., Cary, NC 27513, Molecular and Genetic Epidemiology Section, Epidemiology Branch and Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 and Department of Statistical Science, Duke University, Durham, NC 27708.|Advanced Analytics Division, SAS Institute Inc., Cary, NC 27513, Molecular and Genetic Epidemiology Section, Epidemiology Branch and Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 and Department of Statistical Science, Duke University, Durham, NC 27708.