Affiliation: | 1 Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, U.S.A. huangchi{at}niaid.nih.gov, 2 Department of Biostatistics, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, U.S.A. ncwang{at}jhsph.edu, 3 Department of Biostatistics, University of Iowa, Iowa City, Iowa 52242, U.S.A. ying-j-zhang{at}uiowa.edu |