Department of Statistics, Lowa State University, Ames, Lowa 50011-1210, USA. dnett@iastate.edu|Department of Statistics, Lowa State University, Ames, Lowa 50011-1210, USA. dnett@iastate.edu|Department of Statistics, Lowa State University, Ames, Lowa 50011-1210, USA. dnett@iastate.edu