t</a></span><span class="op">(</span><span class="va">plastic.mod</span>, col<span class="op">=</span><span class="va">colors</span>, cex<span class="op">=</span><span class="fl">1.25</span><span class="op">)</span></span></span>
<span class="r-in"><span><span class="co"># add means for interaction term</span></span></span>
<span class="r-in"><span><span class="va">intMeans</span> <span class="op">&lt;-</span> <span class="fu">termMeans</span><span class="op">(</span><span class="va">plastic.mod</span>, <sp