1 Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC. Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop E-46, Atlanta, GA.
2 Department of Mathematics and Statistics, University of Massachusetts, Amherst. Lederle Graduate Research Tower, Box 34515, University of Massachusetts, Amherst, Amherst, MA 01003.
3 Department of Statistics, University of California Los Angeles. University of California - Los Angeles Department of Statistics 8125 Mathematical Sciences Building Los Angeles, CA 90095.
4 Center for Studies in Demography and Ecology, University of Washington. Raitt Hall 218C, Box 353412, Seattle, WA 98195.