a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/stats/vcov.html" class="external-link">vcov</a></span><span class="op">(</span><span class="va">est</span>, attr <span class="op">=</span> <span class="cn">TRUE</span><span class="op">)</span><span class="op">)</span><span class="op">[</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">"ssc"</span>, <span class="st">"df.K"</span><span class="op