ss="op">=</span><span class="st">"2PL"</span>, maxiter<span class="op">=</span><span class="fl">30</span>, increment.factor<span class="op">=</span><span class="fl">1.03</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">mod2a</span><span class="op">)</span></span>
<span></span>
<span><span class="co">#***</span></span>
<span><span class="co"># Model 3: some fixed c and 