r use of these types of plots can be to interpret power terms, to see the average marginal effect of a variable across values of itself. Consider the following, for example:</p>
<div class="sourceCode"><pre class="sourceCode r"><code class="sourceCode r">x1b &lt;-<span class="st"> </span><span class="kw">lm</span>(mpg <span class="op">~</span><span class="st"> </span>am <span class="op">*</span><span class="st"> </span>wt <span class="op">+</span><span class="st"> </span>am <span class="op">*</span><span cl