l2">
    <p>Estimates the parameters of the classical Heckman sample selection model
using the two-step procedure.</p>
    </div>

    <div class="section level2">
    <h2 id="ref-usage">Usage<a class="anchor" aria-label="anchor" href="#ref-usage"></a></h2>
    <div class="sourceCode"><pre class="sourceCode r"><code><span><span class="fu">twostep</span><span class="op">(</span><span class="va">selection</span>, <span class="va">outcome</span>, data <span class="op">=</span> <span class="fu"><a href="https:/