About the Local G Test

The local G statistics are used to test for spatial clustering (Getis and Ord 1992; Ord and Getis 1995). SpaceStat includes the G and the G*. The G detects rings of high or low values while the G* detects clusters. SpaceStat implements the local G statistics as generalized to more flexible spatial weights as in Ord and Getis (1995).

Examples

Jeffery et al. (2002) used the local G* statistic to examine the spatial pattern of mosquito vectors of the Ross River virus and the Barmah Forest virus on Russell Island, Queensland, Australia. They found significant clustering on the southern end of Russell Island.

Ratcliffe and McCullagh (2001) located hotspots in crime in Nottinghamshire using the local G* statistic. They then compared statistical clusters with the perceived high crime areas.  

Ceccato and Persson (2002) used the local G to study spatial clustering of employment in Sweden. They found clusters of employment in areas with private businesses, and clusters of low employment in areas where the government is the main employer.