n><span class="va">mathgain</span> <span class="op">~</span> <span class="fl">1</span> <span class="op">+</span> <span class="op">(</span><span class="fl">1</span><span class="op">|</span><span class="va">schoolid</span><span class="op">/</span><span class="va">classid</span><span class="op">)</span>, data <span class="op">=</span> <span class="va">classroom</span><span class="op">)</span>
<span class="co"># nlme</span>
<span class="va">fm2.lme</span> <span class="op">&lt;-</span> <span class="fu">nlme</spa