a>  <span class="dt">real</span> log_p = normal_lpdf(y_tilde | alpha + beta * x_tilde, sigma);</span>
<span id="cb1-19"><a href="#cb1-19" aria-hidden="true" tabindex="-1"></a>}</span></code><button title="Copy to Clipboard" class="code-copy-button"><i class="bi"></i></button></pre></div>
<p>Only the training data <code>x</code> and <code>y</code> are used in the model block. The test data <code>y_tilde</code> and test predictors <code>x_tilde</code> appear in only the generated quantities block. Thus the pr