span>, <span class="va">Exam2</span>,  
               na.action <span class="op">=</span> <span class="va">na.exclude</span><span class="op">)</span></code></pre></div>
<p>In the first example, when we try to call <code><a href="../reference/hlm_resid.default.html">hlm_resid()</a></code> on our model object, it throws an informative error asking for the data set used to fit the model. We provide this using the <code>data</code> parameter in the second example.</p>
<div class="sourceCode" id="cb8"><pre clas