First Author:   Paulo M. M. Rodrigues Faculty of Economics, University of Algarve Prodrig@ualg.pt   Faculty of Economics, University of Algarve, Campus de Gambelas Faro, 8005-139, Portugal   00351-289800915(Phone) 00351-289800915(Fax) http://www.ualg.pt/feua/www/prodrig/Paulo.html Second Author: Andrew Tremayne Department of Economics, University of York art7@york.ac.uk   University of York, Department of Economics, Heslington York, YO10 5DD, UK