I have two feature zone data files, both of which are the same except one covers a wider spatial region (ie. it contains a greater number of zones). When I run the Zonal statistics as table tool using a DEM as the input value raster (same in each case), each feature zone file produces slightly different statistics for the identical zones. Why is this? I'd like to know more about the process Arc uses to calculate the stats - does it use only the cell centroids that fall within each zone, or does it include surrounding cells (which will mean that some cells from neighbouring zones will influence the results)? Any tips are appreciated - thanks!