1. Laboratory for Statistics and Computation, ISLA—Instituto Politécnico de Gestão e Tecnologia, Vila Nova de Gaia, Portugal; Integrated Knowledge Systems, Inc., Chatham, IL, USA
2. Laboratory for Statistics and Computation, ISLA—Instituto Politécnico de Gestão e Tecnologia, Vila Nova de Gaia, Portugal; AETHOS Consulting Group, Dallas, TX, USA
3. School of Hotel Administration, SC Johnson College of Business, Cornell University, Ithaca, NY, USA