1. Cox School of Business, Southern Methodist University, Dallas, TX 75275-0333, USA
2. Department of Economics, Kanto Gakuin University, 4834 Mutsuura-machi, Kanazawa-ku, Yokohama 236, Japan
3. Tokyo Metropolitan Institute of Technology, 6–6 Asahigaoka, Hino, Tokyo 191, Japan
4. Helsinki School of Economics and Business Administration, Runeberginkatu 14–16, FIN-00100, Helsinki, Finland