bayesqm - Bayesian Q Methodology: Probabilistic Factor Analysis

A Bayesian factor-analytic framework for Q methodology. Fits a low-rank factor model to Q-sort data with a Student-t likelihood and a hierarchical normal prior on loadings, samples the posterior with Stan, resolves rotational ambiguity via the MatchAlign post-processing of Poworoznek et al. (2025) <doi:10.1214/25-BA1544>, and returns posterior summaries including credible intervals for loadings and factor scores, probabilistic dominant-factor membership, distinguishing and consensus statements, and PSIS-LOO-based factor enumeration following Vehtari et al. (2017) <doi:10.1007/s11222-016-9696-4> with the Sivula et al. (2025) <doi:10.1214/25-BA1569> parsimony rule.