Noriaki Matsushima Institute of Social and Economic Research (ISER), Osaka University   6-1 Mihogaoka Ibaraki, Osaka 567-0047 JAPAN   nmatsush@iser.osaka-u.ac.jp             JEL Areas: L1 : Market Structure, Firm Strategy, and Market Performance: General M0 : Business Administration and Business Economics; Marketing; Accounting: General