><span class="op">}</span></span>
<span></span>
<span><span class="co"># Random intercept model (lifeExp is nested in both countries and years)</span></span>
<span><span class="va">lmer_ri_2</span> <span class="op">&lt;-</span> <span class="kw">function</span><span class="op">(</span><span class="va">formula</span>, <span class="va">data</span>,<span class="va">...</span><span class="op">)</span> <span class="op">{</span></span>
<span>  <span class="kw"><a href="https://rdrr.io/r/base/library.html" class="e