“…They have been widely used in marketing (Lagerkvist et al, 2006;Thong and Hung, 2014;Xu and Wang, 2014), transport, and environmental economics (Adamowicz et al, 1994;Boxall et al, 1996;Hanley et al, 1998;Zander and Garnett, 2011), as well as health economics (Howard and Salkeld, 2009;Rao et al, 2013;Sadique et al, 2013). More recently, they have also been applied to animal science and animal health.…”