1. Department of Statistics and Actuarial Science,University of Iowa,221 Schaeffer Hall, Iowa City, Iowa 52242,U.S.A.jian-huang@uiowa.edu
2. Division of Biostatistics, Department of Epidemiology and Public Health,Yale University,New Haven, Connecticut 06520,U.S.A.shuangge.ma@yale.edu
3. Department of Management Science,University of Miami,Coral Gables, Florida 33124,U.S.A.hxie@exchange.sba.miami.edu
4. Department of Statistics,Rutgers University,Piscataway, New Jersey 08854,U.S.A.cunhui@stat.rutgers.edu