A Bayesian Surrogate Evaluation Test // An implementation of the Bayesian Surrogate Evaluation Test (BSET) for assessing the validity of surrogate markers in clinical trials. Provides hypothesis testing tools to evaluate whether a surrogate can reliably estimate the causal effect of a treatment on a primary outcome. Implements the imputation-based Bayesian methodology of Carlotti and Parast (2026) doi:10.48550/arXiv.2603.14381, extending the frequentist rank-based approach of Parast et al. (2024) doi:10.1093/biomtc/ujad035. Addresses key limitations of the frequentist method, including the lack of causal interpretability and the inability to adjust for covariates in the estimation process.