First Author:   Bhavani Shankar University of Reading b.shankar@reading.ac.uk   Dept. of Ag. & Food Economics, University of Reading, PO Box 237 Reading, RG6 6AR, UK   (+44) 118 378 8298(Phone) (+44) 118 378 8298(Fax) Second Author: Yi Liu University of Reading yiliu@hotmail.ac.uk