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Why do we get different COtypes or outliers on repeating the "Optimized Outlier analysis" and "Cluster and Outlier analysis"

Question asked by poojansh_UNC on Dec 24, 2019
Latest reply on Jan 29, 2020 by JDAcosta-esristaff

Hi all,

I am new to ArcGIS and am looking to find outliers (high and low) in my data. The variable I am using is a disease severity variable ranging from 0 to 60 (i.e. my analysis field). I am trying to find outliers in this variable. However, I recently figured that each time I run the Optimized outlier analysis or the cluster and outlier analysis, there is a good proportion of observations with changed COtypes/p-values, or that I am finding different outlier observations on each run. Although I see that a good proportion are the same when repeated, I am concerned with this change and don't understand why this is happening. I would really appreciate it if anyone could explain why this happens with outlier analysis (Local Moran’s I?) and can I trust that the outliers produced, although different in each run are actually outliers that I can use for my study? Thank you very much for your kind responses.