droom.min.js" integrity="sha256-ZX/yNShbjqsohH1k95liqY9Gd8uOiE1S4vZc+9KQ1K4=" crossorigin="anonymous"></script><!-- pkgdown --><link href="../pkgdown.css" rel="stylesheet"><script src="../pkgdown.js"></script><meta property="og:title" content="cement — cement"><meta property="og:description" content="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 lazil