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Moran's I computed in ArcGIS is different from that in R language (for same dataset)

Question asked by sundeepta on Oct 8, 2012
Latest reply on Jan 15, 2014 by mtuffly
Hi,

I'm trying to get an understanding of global autocorrelation statistics by programatically implementing them.

I'm providing 10 rows of data given here  http://www.ats.ucla.edu/stat/r/faq/morans_i.htm, to ArcGIS (just considered Av8Top,Lat and Lon columns treating them as attribute value (which would be my input field for Moran's I computation), X and Y columns respectively) and then performed the Spatial Autocorrelation (spatial statistics toolbox).

Upon examining the results, the values generated in Arc (expected, observed, p-value and z-score) are not matching with those given on that page which are computed using R language. I have also written a simple java program computing Moran's I using the Global Moran's I explanation given in ArcGIS desktop help. They don't match them either.

It would be extremely helpful if some one can tell me if I'm missing any steps in arriving at the final values that are reported by the Spatial Autocorrelation tool and point me in the right direction.

Also it would be very helpful to have some sample datasets with precomputed autocorrelation statistic values so that I can tally my results with them.

Thanks in advance

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