Identifying local outliers using the Voronoi Map tool

Steps:

1. Click the point or polygon feature layer in the ArcMap table of contents that you want to explore.
2. Click the Geostatistical Analyst drop-down menu on the Geostatistical Analyst toolbar, click Explore Data, then click Voronoi Map.

   When viewing the Voronoi Map, check whether at any vicinity there are polygons with the colors symbolizing very different categories of values. It is data dependable, but in general, a polygon surrounded by others with the values of classes separated by two other classes should catch your attention as indicating a potential outlier.

   Since all but the Simple type of the Voronoi Map are based on the neighborhood calculation, the Simple Voronoi map should be examined in a search of outliers.