.html" class="external-link">vcov</a></span><span class="op">(</span><span class="va">est</span>, ssc <span class="op">=</span> <span class="fu">ssc</span><span class="op">(</span>K.fixef <span class="op">=</span> <span class="st">"none"</span><span class="op">)</span>, attr <span class="op">=</span> <span class="cn">TRUE</span><span class="op">)</span>, <span class="st">"df.K"</span><span class="op">)</span></span></span>
<span class="r-out co"><span class="r-pr">#&gt;</span> [1] 1</span>
<span class="r-in