1. Department of Economics, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK ();
2. ISEG-UL – Universidade de Lisboa; REM – Research in Economics and Mathematics; CEMAPRE – Centro de Matemática Aplicada à Previsão e Decisão Económica, Rua do Quelhas 6, 1200-781 Lisboa, Portugal ();
3. School of Economics, University of Surrey, Guildford GU2 7XH, UK ()