oup.</p></dd>

   <dt id="arg-n-i">n2i<a class="anchor" aria-label="anchor" href="#arg-n-i"></a></dt>
<dd><p>vector of sample sizes for the second group.</p></dd>

   <dt id="arg-ti">ti<a class="anchor" aria-label="anchor" href="#arg-ti"></a></dt>
<dd><p>vector of person-times at risk.</p></dd>

   <dt id="arg-pc">pc<a class="anchor" aria-label="anchor" href="#arg-pc"></a></dt>
<dd><p>control group risk (either a single value or a vector).</p></dd>

   <dt id="arg-pi">pi<a class="anchor" aria-label="anchor"