ader-section-number">17.3.5</span> High <span class="math inline">\(\hat{R}\)</span></h3>
<p><span class="math inline">\(\hat{R}\)</span> (R-hat) convergence diagnostic compares the between- and
within-chain estimates for model parameters and other univariate
quantities of interest. If chains have not mixed well (ie, the
between- and within-chain estimates don’t agree), <span class="math inline">\(\hat{R}\)</span> is larger
than 1. We recommend running at least four chains by default and only
using the sa