[1] Harvard Univ, Dept Stat, Cambridge, MA 02138 USA
[2] UCSD Sch Med, Dept Cellular & Mol Med, La Jolla, CA 92093 USA
[3] Univ Calif San Diego, Bioinformat & Syst Biol Grad Program, La Jolla, CA 92093 USA
[4] Emory Univ, Dept Biostat & Bioinformat, Atlanta, GA 30322 USA