1. Department of Agricultural and Resource Economics, University for Development Studies, Tamale, Ghana
2. Discipline of Agricultural Economics, University of KwaZulu-Natal, P. Bag X01, Scottsville 3209, Pietermaritzburg, South Africa
3. Universite Cheikh Anta Diop, WASCAL GRP-CCE, BP 5683, Dakar-Fann, Senegal