[1] Univ Durham, Business Sch, Dept Econ, Mill Hill Lane, Durham DH1 3LB, England
[2] Univ Politecn Cartagena Murcia, Dept Econ Accounting & Finance, Cartagena 30201, Spain
[3] Univ Politecn Cartagena Murcia, Dept Quantitat Methods Modern Languages & Law, Cartagena 30201, Spain