. year of age, time itself),</p></li>
<li><p>have a <em>joint model</em> for how the covariates and the outcome will change together.</p></li>
</ul>
</div>
<div id="predicting-when-we-know-the-covariate-value-in-advance" class="section level2" number="5.2">
<h2><span class="header-section-number">5.2</span> Predicting when we know the covariate value in advance</h2>
<p>Suppose we have fitted a model with age in years (<code>age</code>) as a time-dependent covariate, e.g. using data like</p>
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