1. Lidong E is a Graduate Student , Jan Hannig is Associate Professor , and Hari Iyer is Professor , Department of Statistics, Colorado State University, Fort Collins, CO 80523. The authors thank the reviewers and the associate editor for their constructive comments and valuable suggestions. Hannig's research was supported in part by National Science Foundation grants 0504737 and 0707037. Iyer's research was funded in part by National Science Foundation grant 0707037.