     longitudinal data data.long</span></span>
<span><span class="co">#############################################################################</span></span>
<span></span>
<span><span class="fu"><a href="https://rdrr.io/r/utils/data.html" class="external-link">data</a></span><span class="op">(</span><span class="va">data.long</span><span class="op">)</span></span>
<span><span class="va">dat</span> <span class="op">&lt;-</span> <span class="va">data.long</span><span class="op">[</span>,<span class="op">-