“…Building off of the tradition of probabilistic topic models, such as the latent Dirichlet allocation model (LDA; Blei, Ng, and Jordan 2003), the correlated topic model (CTM; Blei and Lafferty 2007), and other topic models that have extended these (Mimno and McCallum 2008;Socher, Gershman, Perotte, Sederberg, Blei, and Norman 2009;Eisenstein, O'Connor, Smith, and Xing 2010;Rosen-Zvi, Chemudugunta, Griffiths, Smyth, and Steyvers 2010;Quinn, Monroe, Colaresi, Crespin, and Radev 2010;Ahmed and Xing 2010;Grimmer 2010;Eisenstein, Ahmed, and Xing 2011;Gerrish and Blei 2012;Foulds, Kumar, and Getoor 2015;Paul and Dredze 2015), the structural topic model's key innovation is that it permits users to incorporate arbitrary metadata, defined as infor-mation about each document, into the topic model. With the STM, users can model the framing of international newspapers (Roberts, Stewart, and Airoldi 2016b), open-ended survey responses in the American National Election Study (Roberts et al 2014), online class forums (Reich, Tingley, Leder-Luis, Roberts, and Stewart 2015), Twitter feeds and religious statements (Lucas, Nielsen, Roberts, Stewart, Storer, and Tingley 2015), lobbying reports (Milner and Tingley 2015) and much more. 1 The goal of the structural topic model is to allow researchers to discover topics and estimate their relationship to document metadata.…”