 * am, data = mtcars)</code></pre>
<pre><code>##  at(drat)   drat     wt       am
##      2.76 0.8882 -4.989 -0.04699
##      4.93 0.8882 -7.271 -6.09246</code></pre>
<p>Now <code><a href="../reference/margins.html">margins()</a></code> returns two <code>"margins"</code> objects, one for each combination of values specified in <code>drat</code>. We can see in the above that cars with a low axle ratio (<code>drat == 2.76</code>), the average marginal effect of weight is a reduction in fuel economy of 4.99 mi