rence/cat_analysis.html">cat_analysis()</a></code> and <code><a href="../reference/cont_analysis.html">cont_analysis()</a></code> from the
previous sections, subpopulations and stratification are incorporated
using <code>subpops</code> and <code>stratumID</code>, respectively. For
more on attributable and relative risk in an environmental resource
context, see Van Sickle and Paulsen (2008).</p>
</div>
<div class="section level3">
<h3 id="change-and-trend-analysis">Change and Trend Analysis<a class="anchor" 