e> function does its best. Here we see the marginal effects of a simple regression that includes a factor variable:</p>
<div class="sourceCode"><pre class="sourceCode r"><code class="sourceCode r">x &lt;-<span class="st"> </span><span class="kw">lm</span>(mpg <span class="op">~</span><span class="st"> </span><span class="kw">factor</span>(cyl) <span class="op">*</span><span class="st"> </span>hp <span class="op">+</span><span class="st"> </span>wt, <span class="dt">data =</span> mtcars)
<span class="kw"><a 