 the first visit, as in this artificial dataset:</p>
<div class="sourceCode" id="cb99"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb99-1"><a href="timedep.html#cb99-1" aria-hidden="true" tabindex="-1"></a><span class="fu">head</span>(psor2, <span class="dv">5</span>)</span></code></pre></div>
<pre><code>##   ptnum months state hieffusn ollwsdrt
## 1     1   6.46     1        0        1
## 2     1  17.08     1        1        1
## 3     2  26.32     1        0        0
## 4     2  29.48  