"></a>
</h2>
<p>The default variance estimator in spsurvey is the local neighborhood
variance estimator (Stevens and Olsen, 2003). The local neighborhood
variance estimator incorporates the spatial locations of design sites
into the variance estimation process. Because the local neighborhood
variance estimator incorporates spatial locations, the resulting
variance estimate tends to be smaller than variance estimates from
approaches ignoring spatial locations. The local neighborhood variance
estimator requir