1. INRAN/DECOR, Niamey, Niger; currently at Department of Agricultural Economics, Purdue University, Krannert Bldg., 624, 403 W. State St., West Lafayette, IN 47907‐2056, USA;
2. Department of Agricultural Economics, Purdue University, Krannert Bldg., 609, 403 W. State St., West Lafayette, IN 47907‐2056, USA