ity-parameter" class="section level2">
<h2><span class="header-section-number">5.3</span> Summing out the Responsibility Parameter</h2>
<p>To implement the normal mixture model outlined in the previous
section in Stan, the discrete parameters can be summed out of the
model. If <span class="math inline">\(Y\)</span> is a mixture of <span class="math inline">\(K\)</span> normal distributions with
locations <span class="math inline">\(\mu_k\)</span> and scales <span class="math inline">\(\sigma_k\)</span> with