[1] Koc Univ, Grad Sch Business, TR-34450 Istanbul, Turkey
[2] Jilin Univ, Ctr Quantitat Econ, Changchun 130012, Peoples R China
[3] Jilin Univ, Sch Business, Changchun 130012, Peoples R China
[4] Charles Univ Prague, Fac Math & Phys, Dept Probabil & Math Stat, Prague 18675 8, Czech Republic