mula <span class="op">=</span> <span class="va">w</span> <span class="op">~</span> <span class="va">cf1</span> <span class="op">+</span> <span class="va">cf2</span> <span class="op">+</span> <span class="va">cf3</span> <span class="op">+</span> <span class="va">cf4</span> <span class="op">+</span> <span class="va">cf5</span> <span class="op">+</span> <span class="va">cf6</span>,</span></span>
<span class="r-in"><span>                              gps_density <span class="op">=</span> <span class="st">"norma