span class="op">-</span> <span class="fu"><a href="https://rdrr.io/r/base/colSums.html" class="external-link">rowMeans</a></span><span class="op">(</span><span class="va">phi</span><span class="op">)</span></span>
<span><span class="co"># rater variability parameters</span></span>
<span><span class="va">psi</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/matrix.html" class="external-link">matrix</a></span><span class="op">(</span> <span class="fu"><a href="https://rdrr.