bayes_R2: Computes R-squared using Bayesian R-squared approach.
Description
For detail refer to:
Andrew Gelman, Ben Goodrich, Jonah Gabry, and Aki Vehtari (2018).
R-squared for Bayesian regression models. The American Statistician
tools:::Rd_expr_doi("10.1080/00031305.2018.1549100") and
https://avehtari.github.io/bayes_R2/bayes_R2.html