#&gt;</span>     max, mean, min, prod, range, sample, sum</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>   response substance female male prop_female_prop_female</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 1      sex   alcohol     36  141               0.2033898</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 2      sex   cocaine     41  111               0.2697368</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 3      sex    heroin     30   94   