1. Department of Economics, Universidade Católica de Brasília, QS 7 Lote 1, EPCT, Águas Claras, Brasília 71966-900, DF, Brazil
2. University of Madeira, 9000-082 Funchal, Portugal
3. Interactive Technologies Institute (ITI/LARSyS and ARDITI), 9020-105 Funchal, Portugal