The local Moran test (Anselin 1995) detects local spatial autocorrelation in group-level data. It is related to Moran's I (Moran 1950), a test for global spatial autocorrelation. In essence, the local Moran decomposes Moran's I into contributions for each location, termed LISAs, for Local Indicators of Spatial Association. These indicators detect clusters of either similar or dissimilar disease frequency values around a given observation. While LISA statistics can be developed for a number of statistics (Anselin 1995), ClusterSeer implements the LISA for Moran's I.
The sum of LISAs for all observations is proportional to Moran's I, an indicator of global pattern. Thus, there can be two interpretations of LISA statistics, as indicators of local spatial clusters and as a diagnostic for outliers in global spatial patterns.
