Three main text-based approaches are: (1) the use of gazetteers Quercini et al., 2010) ; (2) unsupervised text clustering based on topic models or similar<cite> (Eisenstein et al., 2010</cite>; Hong et al., 2012; Ahmed et al., 2013) ; and (3) supervised classification (Ding et al., 2000; Backstrom et al., 2008; Cheng et al., 2010; Hecht et al., 2011; Kinsella et al., 2011; Wing and Baldridge, 2011; Han et al., 2012; Rout et al., 2013) , which unlike gazetteers can be applied to informal text and compared to topic models, scales better.