[1] Queens Univ, Dept Econ, Dunning Hall Room 303, Kingston, ON K7L 3N6, Canada
[2] East China Normal Univ, Fac Educ, Shanghai, Peoples R China
[3] Beijing Normal Univ, Fac Educ, Beijing, Peoples R China
[4] Natl Innovat Ctr Basic Educ, Beijing, Peoples R China