Classification Statistics vs. Zonal Statistics

Discussion created by nrcesri on Apr 17, 2012
Latest reply on Jun 21, 2012 by erice-esristaff
Hi everyone,

I am trying to calculate the mean population density of India given a population density layer (raster) and the country's border (shapefile). In order to do this, I ran the zonal statistics as table tool, where the zone layer was the shapefile and the value layer was the population density layer. This worked and I got the statistics. However, I remembered that Arc also calculates classification statistics when prompted. After doing so for the population density layer, the classification statistics look quite different than those given by the zonal statistics table (min and max values are the same but otherwise the rest are different!). I think this might be because I chose to ignore NoData during the zonal statistics step. Is that possible?
Can anyone explain the difference in results or have any thoughts?  

Thank you for your help and thoughts!! I appreciate it.