n class="op">$</span>drat), <span class="dt">am =</span> <span class="dv">0</span><span class="op">:</span><span class="dv">1</span>))
<span class="kw">nrow</span>(m1)<span class="op">/</span><span class="kw">nrow</span>(mtcars)</code></pre></div>
<pre><code>## [1] 40</code></pre>
<p>As you can see above, the result is a relatively long data frame (basically a stack of <code>"margins"</code> objects specific to each of the - 40 - requested combinations of <code>at</code> values). We can examine the whole st