Division of Biostatistics, University of California-Davis, Davis, CA, USA. dmrocke@ucdavis.edu|Division of Biostatistics, University of California-Davis, Davis, CA, USA. dmrocke@ucdavis.edu|Division of Biostatistics, University of California-Davis, Davis, CA, USA. dmrocke@ucdavis.edu|Division of Biostatistics, University of California-Davis, Davis, CA, USA. dmrocke@ucdavis.edu