en name"><code>cement.Rd</code></div>
    </div>

    <div class="ref-description">
    <p>Wooldridge Source: J. Shea (1993), “The Input-Output Approach to Instrument Selection,” Journal of Business and Economic Statistics 11, 145-156. Professor Shea kindly provided these data. Data loads lazily.</p>
    </div>

    <div id="ref-usage">
    <div class="sourceCode"><pre class="sourceCode r"><code><span><span class="fu"><a href="https://rdrr.io/r/utils/data.html" class="external-link">data</a></span><span