KAldous

Moran's I - non-negative values only?

Discussion created by KAldous on Apr 25, 2013
Hello,

I've been exploring SAC for some project data and just came across this line in the Moran's I tool help page:

"The input field should contain a variety of non-negative values."

http://resources.esri.com/help/9.3/arcgisengine/java/Gp_ToolRef/spatial_statistics_tools/spatial_autocorrelation_morans_i_spatial_statistics_.htm

Could someone please help to explain this requirement?  My thoughts are that maybe the tool does not use the absolute value for the variance between data points?  I am trying to look at hot/cold spots in trend data (% change per year) which does have negatives.  I could add a positive value to the input field to get positive values (i.e. add the minimum negative value to all data points) however I'm not sure how this would affect my results.  Any suggestions?

Thanks in advance,
Kristin

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