one potential confounding variable among others (age, smoking, etc.)
that might be useful to control statistically.</p>
<p>Friendly et al. (2013) use this data to illustrate
(a) data ellipses in data space and the corresponding confidence ellipses in
parameter (\(\beta\)) space; (b) effects of measurement error in a predictor or response;
(c) added-variable plots and more.</p>
    </div>
    <div class="section level2">
    <h2 id="source">Source<a class="anchor" aria-label="anchor" href="#source"></a></h2>