>"power"</span><span class="op">]</span><span class="op">]</span></span>
<span></span>
<span><span class="va">n_control_exposed</span> <span class="op">&lt;-</span> <span class="va">contraceptives</span><span class="op">[</span><span class="fl">1</span>, <span class="fl">2</span>, <span class="op">]</span></span>
<span><span class="va">n_control_total</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/apply.html" class="external-link">apply</a></span><span class="op">(</sp