Mengdan Li Department of Economics and Business, Hokkaido University   No.408, Northtown House Kita11 Nishi3 Kita-ku Sapporo, Hokkaido 001-0011 Japan   Mengdannew@eis.hokudai.ac.jp             JEL Areas: J7 : Labor Discrimination: General J3 : Wages, Compensation, and Labor Costs: General