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Bug

An outlier analysis using the 'Cluster and Outlier Analysis (Anselin Local Moran's I)' geoprocessing tool in ArcGIS Pro and the Find Outliers tool in ArcGIS Online shows different outputs.

Last Published: December 15, 2022 ArcGIS Online
Bug ID Number BUG-000143785
SubmittedOctober 19, 2021
Last ModifiedJune 22, 2026
Applies toArcGIS Online
Version found9.3
Operating SystemWindows OS
Operating System Version10.0
StatusAs Designed

Additional Information

The difference does not indicate an accuracy issue. Although the same statistic is used, statistical significance is evaluated through a random permutation process, so small variations in results are expected. These differences can occur between runs or environments, especially for features near significance thresholds. Even with the same random seed, results are not guaranteed to be identical across systems because floating‑point calculations are handled slightly differently by different processors. It’s also important to note that input data uncertainty plays a role. Census data and similar inputs are themselves estimates and contain inherent uncertainty, which can influence results when values are close to classification boundaries. To better understand how sensitive results are to attribute uncertainty, ArcGIS Pro 3.4 introduces the Assess Sensitivity to Attribute Uncertainty tool available at https://pro.arcgis.com/en/pro-app/latest/tool-reference/spatial-statistics/how-assess-sensitivity-to-attribute-uncertainty-works.htm. This tool helps quantify how much analysis results may vary due to uncertainty in the input data and can provide additional context when interpreting outliers or clusters. Overall, the observed differences reflect the combined effects of random significance testing and data uncertainty, rather than any inconsistency in how the underlying statistic is calculated.

Steps to Reproduce

Bug ID: BUG-000143785

Software:

  • ArcGIS Online

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