Department of Statistics, Texas A&M University, 447 Blocker Building, College Station, TX 77843, USA. wfu@stat.tamu.edu|Department of Statistics, Texas A&M University, 447 Blocker Building, College Station, TX 77843, USA. wfu@stat.tamu.edu|Department of Statistics, Texas A&M University, 447 Blocker Building, College Station, TX 77843, USA. wfu@stat.tamu.edu|Department of Statistics, Texas A&M University, 447 Blocker Building, College Station, TX 77843, USA. wfu@stat.tamu.edu