GEORGE E. P. BOX, PhD, DSc, FRS, is Ronald Aylmer Fisher Professor Emeritus of Statistics and Industrial Engineering at the University of Wisconsin-Madison. He is a Fellow of the Royal Society, an Honorary Fellow and Shewhart and Deming Medalist of the American Society for Quality, and was awarded the Guy Medal in Gold from the Royal Statistical Society. He is also the recipient of the Samuel S. Wilks Memorial Medal of the American Statistical Association.NORMAN DRAPER is Professor Emeritus of Statistics in the Department of Statistics at the University of Wisconsin, Madison. He received his PhD from the University of North Carolina, Chapel Hill, and has published dozens of papers in professional journals. He is the coauthor (with Harry Smith) of Applied Regression Analysis, Third Edition, published by Wiley.