Affiliation: | (1) Department of Biostatistics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7400, USA, e-mail;(2) Department of Statistics and Applied Probability, National University of Singapore, 3 Science Drive 2, Singapore, 117543, Singapore;(3) School of Mathematics and Statistics, The University of Birmingham, Birmingham, B15 2TT, UK |