1. Wilson W. Lu is Postdoctoral Fellow, Department of Statistics and Actuarial Science, Simon Fraser University, Burnaby, BC, Canada V5A 1S6 . J. Michael Brick is Vice-President, Westat, Inc., Rockville, MD 20850-3129 . Randy R. Sitter is Professor, Department of Statistics and Actuarial Science, Simon Fraser University, Burnaby, BC, Canada V5A 1S6 . This research was supported by grants from the Natural Sciences and Engineering Research Council of Canada. The authors thank the associate editor and two...