1. School of Economic Sciences, Washington State University, Pullman, Washington 99164;
2. Economics and Management of Agrobiotechnology Center, University of Missouri, Columbia, Missouri 65211;
3. Department of Economics and LICOS Centre for Institutions and Economic Performance, KU Leuven, Leuven, B-3000 Belgium;
4. Center on Food Security and the Environment, Stanford University, Stanford, California 94305