“…These survey methods have major shortcomings such as small sample rates, short survey durations, under-reporting and a high cost (Calabrese et al, 2011). Meanwhile, a variety of other data sources has been used, such as circulating bank notes (Brockmann et al, 2006), Foursquare check-in data (Noulas et al, 2012), tweets (Hawelka et al, 2014;Mahmud et al, 2014;Hironaka et al, 2016) and GPS data (Vazquez-Prokopec et al, 2013;Tang et al, 2015).…”