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Local Indicators of Spatial Autocorrelation (LISA) Autocorrelation Distance.

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Presentation on theme: "Local Indicators of Spatial Autocorrelation (LISA) Autocorrelation Distance."— Presentation transcript:

1 Local Indicators of Spatial Autocorrelation (LISA) Autocorrelation Distance

2 Conceptualization of Spatial Relationships INVERSE_DISTANCE—Nearby neighboring features have a larger influence on the computations for a target feature than features that are far away. INVERSE_DISTANCE_SQUARED—Same as INVERSE_DISTANCE except that the slope is sharper, so influence drops off more quickly. FIXED_DISTANCE_BAND—Each feature is analyzed within the context of neighboring features. Neighboring features inside the specified critical distance receive a weight of 1. ZONE_OF_INDIFFERENCE—Features within the specified critical distance of a target feature receive a weight of 1 and once the critical distance is exceeded, weights diminish with distance. CONTIGUITY_EDGES_ONLY—Only neighboring polygon features that share a boundary or overlap will influence computations for the target polygon feature. CONTIGUITY_EDGES_CORNERS—Polygon features that share a boundary, share a node, or overlap will influence computations for the target polygon feature. GET_SPATIAL_WEIGHTS_FROM_FILE—Spatial relationships are defined in a spatial weights file. The path to the spatial weights file is specified in the Weights Matrix File

3 Distance Tools Calculate Distance Band from Neighbor Count Returns the minimum, the maximum, and the average distance to the specified Nth nearest neighbor (N is an input parameter) for a set of features. Incremental Spatial Autocorrelation Measures spatial autocorrelation for a series of distances and optionally creates a line graph of those distances and their corresponding z-scores. Z-scores reflect the intensity of spatial clustering, and statistically significant peak z-scores indicate distances where spatial processes promoting clustering are most pronounced. These peak distances are often appropriate values to use for tools with a Distance Band or Distance Radius parameter.

4 Random Pottery Example Calculate Distance Band from Neighbor Count Minimum Distance – 200 meters Average Distance – 561 meters Can be used as an interval to determine correlation distances Maximum Distance – 1166 meters The start to determine correlation distances Incremental Spatial Autocorrelation Beginning Distance: 1200 Distance Increment: 600 Euclidean Distance

5 Random Pottery Example Incremental Spatial Autocorrelation

6 Hot Spot Analysis (Getis-Ord Gi*)

7 Tucson Census Tract Data – Fraction of Hispanic Calculate Distance Band from Neighbor Count Minimum Distance: 626 meters Average Distance: 1630 meters Maximum Distance: 6814 meters Incremental Spatial Autocorrelation

8 High-Low Clustering Fixed Distance Extent Contiguity Edges Corners

9 Hot Spot Analysis Fixed Distance ExtentContiguity Edges Corners


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