id childid</span>
<span class="co">#&gt; 1     160        1       1</span>
<span class="co">#&gt; 2     160        1       2</span>
<span class="co">#&gt; 3     160        1       3</span>
<span class="co">#&gt; 4     217        1       4</span>
<span class="co">#&gt; 5     217        1       5</span>
<span class="co">#&gt; 6     217        1       6</span></code></pre></div>
<p>The data set contains 12 columns; however, we are only interested in the response variable, <code>mathgain</code>, and the groupin