s</span><span class="op">)</span></span>
<span class="r-in"></span>
<span class="r-in"></span>
<span class="r-in"><span class="co"># simulate non-randomized treatment</span></span>
<span class="r-in"><span class="va">xbetat</span>   <span class="op">&lt;-</span> <span class="fl">0.5</span> <span class="op">+</span> <span class="fl">0.5</span> <span class="op">*</span> <span class="va">x</span><span class="op">[</span>,<span class="fl">11</span><span class="op">]</span> <span class="op">-</span> <span class=