Zonal statistics as table does not produce correct results

Discussion created by au on Feb 6, 2012
Latest reply on Dec 3, 2014 by curtvprice

I am trying to produce zonal statistics as table using a polygon shapefile and a raster as input. First I used 'extract by mask' to extract the appropriate cells from a global raster dataset and this works fine as ArcMap extracts all (and only) the cells that have their centre within the polygons. However, when I produce the zonal stats the results are not correct. Too many or too few cells are included in the count and the sum and other statistics are wrong for some (but not all) polygons. Both the shapefile and raster are in the same coordinate system (GCS WGS 1984) and I use the default settings for this tool. Does anyone have any ideas what might be causing this error? Any help appreciated!