me, we refer to models with <em>no explanatory variables</em>. In such models, a simple <code>1</code> goes to the right of the <img src="www/tilde.png" class="img-fluid" alt="tilde">. The reasons for doing this require some explanation, which will be provided in later Lessons.</p>
</section>
<section id="shapes-of-models" class="level2 page-columns page-full">
<h2 class="anchored" data-anchor-id="shapes-of-models">“Shapes” of models</h2>
<p>Although the response variable in a regression model is always