1. Institute of Developing Economies, Japan External Trade Organization, 16th Floor, Nantawan Building, 161 Rajadamri Road, Pathumwan, Bangkok 10330, Thailand; e-mail: kazunobu_hayakawa@ide-jetro.org and bKeio Economic Observatory, Keio University, Japan, 2-15-45, Mita, Minato-ku, Tokyo, 108-8345, Japan; e-mail: matsuura@sanken.keio.ac.jp