pan>无偏差，高方差。</p>
<p>我们采用加权平均值<span ><span class="katex"><span aria-hidden="true" class="katex-html"><span class="base"><span class="strut" style="height:1.5539959999999997em;vertical-align:-0.24575599999999997em;"></span><span class="mord coloredeq eqh" style=""><span class="mord accent" style=""><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:1.3082399999999998em;"><span style="top:-3.0448em;"><span class="pstrut" style="height:3.0448