an class="va">variance.fixed</span>,</span>
<span>              b.init<span class="op">=</span><span class="va">b.init</span>, a.init<span class="op">=</span><span class="va">a.init</span>, maxiter<span class="op">=</span><span class="fl">20</span>, est.a<span class="op">=</span><span class="st">"2PL"</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">mod8b</span><span 