ixed<span class="op">=</span><span class="va">variance.fixed</span>,</span>
<span>            maxiter<span class="op">=</span><span class="fl">30</span><span class="op">)</span></span>
<span><span class="fu"><a href="https://rdrr.io/r/base/summary.html" class="external-link">summary</a></span><span class="op">(</span><span class="va">mod8</span><span class="op">)</span></span>
<span></span>
<span><span class="co">#***</span></span>
<span><span class="co"># Model 8b: 2PL model with starting values for a and 