“…There are a lot of IRT specific software packages available, in particular in the programming language R (R Core Team 2019), for example, mirt (Chalmers 2012), sirt (Robitzsch 2019), or TAM (Robitzsch et al 2019; see Bürkner 2019 for a detailed comparison). In addition to these more specialized packages, general purpose probabilistic programming languages can be used to specify and fit Bayesian IRT models, for example, BUGS (Lunn et al 2009; see also Curtis 2010), JAGS (Plummer 2013; see also Depaoli et al 2016;Zhan et al 2019), or Stan (Carpenter et al 2017; see also Allison and Au 2018; Luo and Jiao 2018). In this paper, I use the brms package (Bürkner 2017(Bürkner , 2018, a higher level interface to Stan, which is not focused specifically on IRT models but more generally on (Bayesian) regression models.…”