1. Graduate Student, Department of Economics and Graduate Associate at the Center for Policy Research, Maxwell School of Citizenship and Public Affairs, Syracuse University, Syracuse, New York, USA. I wish to thank Mark Rosenzweig, Dani Rodrik and Robert T. Jensen for thought provoking discussions that increased my interest and awareness of these issues. I also thank Gary Engelhardt, Jesse Bricker, Katie Fitzpatrick and two anonymous referees for very helpful comments. Correspondence can be sent to: Center...