1. Department of Statistics; Kansas State University; Manhattan, KS 66506, USA
2. Division of Epidemiology, Biostatistics, and Environmental Health; University of Memphis; Memphis, TN 38111, USA
3. Department of Statistics and Probability; Michigan State University; 619 Red Cedar Rd East Lansing, MI 48824, USA
4. Department of Biostatistics; Yale University; 60 College Street New Haven, CT 06520, USA