er <a href="activity.html#activity">6</a>). The example below calculates the PHQ-9 sum scores from the item scores in the cleaned baseline (t0) and post-test (t1) data:</p>
<div class="sourceCode"><pre class="sourceCode r"><code class="sourceCode r"><span class="co"># ------------------------------------------------------------</span>
<span class="co"># Pre-process survey data </span>
<span class="co"># JR - 2018-10-16</span>
<span class="co"># ------------------------------------------------------------</s