an class="va">Z</span><span class="op">)</span>, <span class="op">-</span><span class="fu"><a href="../reference/QR.html">QR</a></span><span class="op">(</span><span class="va">X</span><span class="op">)</span><span class="op">$</span><span class="va">Q</span> <span class="op">)</span></span></code></pre></div>
<pre><code><span><span class="co">## [1] TRUE</span></span></code></pre>
</div>
</div>
<div class="section level2">
<h2 id="regression-with-x-and-z">Regression with X and Z<a class="anchor" aria-labe