1. Department of Economics and The Fletcher School, Tufts University, 160 Packard Avenue, Medford, MA 02155.
2. Centre for the Study of African Economies (CSAE), Department of Economics, University of Oxford, Manor Road, Oxford OX1 3UQ.
3. Department of Agricultural and Resource Economics, University of California-Davis, 1 Shields Avenue, Davis, CA 95616 and Giannini Foundation of Agricultural Economics.