&gt; <span style="color: #BCBCBC;">5</span> gdpPercap_log lifeExp lmer_rs_1 no covariates all     lifeExp ~ gdpPercap_log…</span></span>
<span><span class="co">#&gt; <span style="color: #BCBCBC;">6</span> gdpPercap_log lifeExp lmer_rs_1 pop           all     lifeExp ~ gdpPercap_log…</span></span></code></pre></div>
</div>
<div class="section level3">
<h3 id="fit-the-models">Fit the models<a class="anchor" aria-label="anchor" href="#fit-the-models"></a>
</h3>
<p>Now, we can simply fit the models with <co