n><span class="op">)</span></span></span>
<span class="r-in"><span></span></span>
<span class="r-in"><span><span class="co">#read in data </span></span></span>
<span class="r-in"><span><span class="fu"><a href="https://rdrr.io/pkg/EdSurvey/man/downloadPISA.html" class="external-link">downloadPISA</a></span><span class="op">(</span><span class="st">"~/"</span>, year<span class="op">=</span><span class="fl">2012</span><span class="op">)</span></span></span>
<span class="r-in"><span><span class="va">cntl</span