=</span> <span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="st">"regressors"</span>, <span class="st">"projected"</span>, <span class="st">"instruments"</span><span class="op">)</span>,</span>
<span>  <span class="va">...</span></span>
<span><span class="op">)</span></span>
<span></span>
<span><span class="co"># S3 method for ivreg_projected</span></span>
<span><span class="fu"><a href="https://rdrr.io/r/stats/model.matrix.html" c