David W. Stewart is the Robert E. Brooker Professor of Marketing and Deputy Dean of Faculty in the Marshall School of Business. Comments regarding this manuscript should be directed to David W. Stewart, Marshall School of Business, Office of the Deputy Dean, HOH700B, University of Southern California, Los Angeles, CA 90089-1426. Telephone: (213) 740-5037. Facsimile: (213) 740-6465. E-mail: David.Stewart@Marshall.USC.EDU. 46