><span class="op">(</span><span class="va">pc</span><span class="op">)</span></span></code></pre></div>
<p><img src="vtablehelpers_files/figure-html/unnamed-chunk-3-1.png" width="700"></p>
</div>
<div class="section level3">
<h3 id="weighted-sd">
<code>weighted.sd</code><a class="anchor" aria-label="anchor" href="#weighted-sd"></a>
</h3>
<p><code>weighted.sd(x, w)</code> is a function to calculate a weighted
standard deviation of <code>x</code> using <code>w</code> as weights,
much like the base <code><a hr