1. Hua Liang is Associate Professor and Hulin Wu is Professor , Department of Biostatistics and Computational Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642. The authors would like to thank Yun Fang for her careful reading of an earlier version of this manuscript and her help in correcting an error in the theoretical results. The authors are also grateful to an associate editor and three referees for their constructive comments and suggestions. This research was...