I recently need to calculate Moran's Index in ArcGIS 10.2. However, I found that the results in ArcGIS and GeoDa were different. My spatial weight matrix was 4-nearest neighbors matrix. And I also found that as the number of nearest neighbors increasing, the difference would increase. I guess this is because of projected coordinate system, but I don't know which result is correct. Anyone who can tell me? If the result of GeoDa is correct, how can we correct the calculation in ArcGIS? Thank you so much!!