First Author:   Munetomo Ando Graduate School of Economics, University of Tokyo munetomo@grad.e.u-tokyo.ac.jp   Hongo 7-3-1, Bunkyo-ku Tokyo, 113-0033, Japan       http://www.grad.e.u-tokyo.ac.jp/~munetomo/ Second Author: Daisuke Oyama Graduate School of Economics, University of Tokyo doyama@grad.e.u-tokyo.ac.jp   Hongo 7-3-1, Bunkyo-ku Tokyo, 113-0033, Japan       http://www.grad.e.u-tokyo.ac.jp/~doyama/