><span class="op">)</span></span></span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 'data.frame':	14583 obs. of  9 variables:</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>  $ ID       : Factor w/ 3146 levels "2000.10001.F",..: 1 1 1 1 2 2 3 3 3 3 ...</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>  $ Year     : int  2000 2000 2000 2000 2000 2000 2000 2000 2000 2000 ...</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>  $ Sex      : Factor w/ 2 levels "F"