Indicators of spatial association are statistics that evaluate the existence of clusters in the spatial arrangement of a given variable. For instance, if we are studying cancer rates among census tracts in a given city local clusters in the rates mean that there are areas that have higher or lower rates than is to be expected by chance alone; that is, the values occurring are above or below those of a random distribution in space.
Global indicators
Spatial Autocorrelation Report generated by ArcGIS Pro for 2022 U.S. county population
Notable global indicators of spatial association include:
Geary's C (Geary's Contiguity Ratio): A measure of global spatial autocorrelation developed by Roy C. Geary in 1954. It is inversely related to Moran's I, but more sensitive to local autocorrelation than Moran's I.
Getis–Ord G (Getis–Ord global G, Geleral G-Statistic): Introduced by Arthur Getis and J. Keith Ord in 1992 to supplement Moran's I.
Local indicators
Clusters of the estimated percent of people in poverty by county in the contiguous United States in 2020HotSpot map of the estimated percent of non-institutionalized population without health insurance, by county in the contiguous United States in 2020
Notable local indicators of spatial association (LISA) include:
Local Moran's I: Derived from Global Moran's I, it was introduced by Luc Anselin in 1995 and can be computed using GeoDa.
Getis–Ord Gi (local Gi): Developed by Getis and Ord based on their global G.
INDICATE's IN: Originally developed to assess the spatial distribution of stars, can be computed for any discrete 2+D dataset using python-based INDICATE tool available from GitHub.
↑J. N. R. Jeffers (1973). "A Basic Subroutine for Geary's Contiguity Ratio". Journal of the Royal Statistical Society, Series D. 22 (4). Wiley: 299–302. doi:10.2307/2986827. JSTOR2986827.
↑Getis, Arthur; Ord, J. Keith (1992). "The analysis of spatial association by use of distance statistics". Geographical Analysis. 24 (3): 189–206. doi:10.1111/j.1538-4632.1992.tb00261.x.