Thank you to everyone who replied with great answers. We have looked at the problem in more detail and for the size matrices we will have will a brute force (try all orders) approach will work and give us the best answer. Bill --- Biostatistics Consulting Center http://ilya.wustl.edu/~shannon/bcc_announcement.pdf William D. Shannon, Ph.D. Associate Professor of Biostatistics in Medicine Division of General Medical Sciences and Biostatistics Washington University School of Medicine Campus Box 8005, 660 S. Euclid St. Louis, MO 63110 Phone: 314-454-8356 Fax: 314-454-5113 e-mail: [log in to unmask] web page: http://ilya.wustl.edu/~shannon