Affiliation: | (1) Faculty of Economics and Business Administration, Hokkaido University, Nishi 7, Kita 9, Kita-ku, Sapporo 060-0809, Japan (e-mail: hasegawa@econ.hokudai.ac.jp; kozumi@econ.hokudai.ac.jp), JP;(2) Faculty of Economics, Kansai University, 3-3-35 Yamata, Suita, Osaka 564–8680, Japan (e-mail: t902375@kansai-u.ac.jp), JP |