A 1 4.041452</span></span></code></pre></div>
<p>Here <code>n</code> becomes <code>NA</code> because <code>n</code> is
numeric, so the <code>across()</code> computes its standard deviation,
and the standard deviation of 3 (a constant) is <code>NA</code>. You
probably want to compute <code>n()</code> last to avoid this
problem:</p>
<div class="sourceCode" id="cb13"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>df <span class="sc">%&gt;%</span> </sp