e doesn’t affect transition rates between effusion states, but the effusion state affects the rates of progression of joint damage. The appropriate assumption depends on the clinical application.</li>
</ul>
</div>
<div id="time-itself-as-a-covariate" class="section level2" number="5.4">
<h2><span class="header-section-number">5.4</span> Time itself as a covariate</h2>
<p>Could easily fit a model with the time of the observation as a covariate (<code>months</code> in this example), with a linear effect on 