Peter S.H. Leeflang (1946) is Professor of Marketing at the Department of Economics at the University of Groningen, The Netherlands, and member of the Royal Netherlands Academy of Arts and Sciences. Dick R. Wittink (1945) is the General George Rogers Clark Professor of Management and Marketing at the Yale School of Management, USA, and Professor of Marketing and Marketing Research at the University of Groningen, The Netherlands Michel Wedel (1957) is Professor of Marketing Research at the Department of Economics, University of Groningen, The Netherlands. Philippe A. Naert (1945) is the Dean of...