021).  See that paper for additional descriptions.</p>
    </div>

    <div id="ref-usage">
    <div class="sourceCode"><pre class="sourceCode r"><code><span><span class="va">mpdta</span></span></code></pre></div>
    </div>

    <div id="format">
    <h2>Format</h2>
    <p>A data frame with 2000 rows and 5 variables:</p><dl><dt>year</dt>
<dd><p>the year of the observation</p></dd>

<dt>countyreal</dt>
<dd><p>a unique identifier for a particular county</p></dd>

<dt>lpop</dt>
<dd><p>the log of 1000s of popu