pan class="fu"><a href="https://rdrr.io/r/graphics/plot.default.html" class="external-link">plot</a></span><span class="op">(</span><span class="va">sma_brainBody</span>,which<span class="op">=</span><span class="st">"residual"</span><span class="op">)</span> <span class="co"># residual plot</span></span>
<span><span class="fu"><a href="https://rdrr.io/r/graphics/abline.html" class="external-link">abline</a></span><span class="op">(</span>a<span class="op">=</span><span class="fl">0</span>,b<span class="op"