@INBOOK {MUTSAERS:1991, title = {Farmer-related variables in on-farm trials: their measurement and use in statistical analyses}, author = {Mutsaers, H. J. W. }, year = {1991}, type = {On-farm research in theory and practice, edited by H.J.W. Mutsaers and P. Walker}, pages = {46--52}, publisher = {International Institute of Tropical Agriculture (IITA)}, address = {Ibadan, Nigeria}, }