1. Computer Science Department, University of the Balearic Islands, 07122 Palma, Spain
2. Research Centre School, Hotelschool The Hague, 2587 AH The Hague, The Netherlands
3. LAB8 Service Experience Laboratory, Haaga-Helia University of Applied Sciences, 00520 Helsinki, Finland
4. School of Tourism and Hospitality Management, Technological University Dublin, D07 EWV4 Dublin, Ireland