span class="op">+</span> <span class="va">b</span><span class="op">*</span><span class="va">x_2</span> <span class="op">+</span> <span class="va">a</span><span class="op">*</span><span class="va">x_3</span> <span class="op">+</span> <span class="va">b</span><span class="op">*</span><span class="va">x_4</span><span class="op">)</span></span></span>
<span class="r-in"><span><span class="va">res</span> <span class="op">&lt;-</span> <span class="fu"><a href="estimate_lavaan.html">estimate_lavaan</a></span><spa