r-fourpno (conda): Estimate Barton & Lord's (1981) <doi:10.1002/j.2333-8504.1981.tb01255.x> four parameter IRT model with lower and upper asymptotes using Bayesian formulation described by Culpepper (2016) <doi:10.1007/s11336-015-9477-6>.
Keywords: armadillo|cognitive-diagnostic-models|gibbs-sampler|item-response-theory|r|rcpp|rcpparmadillo|rstats