[1] Stanford University AIDS Clinical Trials Unit, Stanford University, Stanford, CA
[2] Statistical and Data Analysis Center, Harvard School of Public Health, Boston, MA
[3] University College Dublin, Belfield
[4] University of Southern California, Los Angeles, CA
[5] Wits Health Consortium, Helen Joseph Hospital, Johannesburg
[6] Frontier Science and Technology Research Foundation, Amherst, NY
[7] Social and Scientific Systems, Inc., Silver Spring, MD
[8] Statistical and Data Analysis Center, Harvard School of Public Health, Boston, MA