" class="external-link">describe</a></span><span class="op">(</span><span class="va">dat</span><span class="op">)</span></span>
<span></span>
<span><span class="co">#******************</span></span>
<span><span class="co">#*** Model 1: Partial credit model</span></span>
<span><span class="va">lavmodel</span> <span class="op">&lt;-</span> <span class="st">"</span></span>
<span><span class="st">      O=~ 1*O3+1*O8+1*O13+1*O18+1*O23+1*O28</span></span>
<span><span class="st">      O ~~ O</span></span>
<span><s