> contribute significantly in describing GCSE exam scores, so we incorporate these terms in the updated model, <code>fm1b</code>. We then reassess the level-1 LS residuals.</p>
<div class="sourceCode" id="cb17"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span class="va">fm1b</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/stats/update.html">update</a></span><span class="op">(</span><span class="va">fm1</span>, <span class="va">.</span><span class="op">~</s