1. Birmingham Business School, Birmingham, UK
2. Dipartimento di Scienze Economico-sociali e Matematico-statistiche, Universita' di Torino, Turin, Italy
3. Department of Philosophical, Pedagogical and Economic-Quantitative Sciences, University of Chieti-Pescara, Pescara, Italy
4. Department of Economics and Statistics, University of Siena, Siena, Italy