Getis-Ord Gi* is used to find hotspots and coldspots of a feature in
space. A hotspot is a cluster of high values in space, and a coldspot is
a cluster of low values in space. Getis-Ord Gi* is essentially the
z-score of the spatially lagged value of the feature at each location
\(i\) ($*j w*{ij}x_j $), where
\(w_{ij}\) is the spatial weight. In
the original
publication for Getis-Ord Gi* from 1992 (Getis and Ord 1992), the spatial weight is a
distance-based binary weight indicating whether another location is
within a certain distance from each location \(i\). Getis-Ord Gi excludes the location
\(i\) itself in the computation of mean
and variance of the lagged value, while Gi* includes the location \(i\) itself. Usually Gi and Gi* yield
similar results. The mean and variance used in the z-score differ in Gi
and Gi* and is described in this
paper from 1995 (Ord and Getis 1995)
and derived in (Getis and Ord 1992).
Binary weights in the spatial neighborhood graph are recommended for
Getis-Ord Gi*.

Below is a list of vignettes that use Getis-Ord Gi*. The links point to the sections that use Getis-Ord Gi*. The corresponding Google Colab notebooks are also linked to. The list is sorted by technology.

Vignette | Colab Notebook | Description |
---|---|---|

Spatial Visium exploratory data analysis | Colab Notebook | Getis-Ord Gi* of gene Myh2 (myosin heavy chain 2) in mouse skeletal muscle dataset |

## References

*Perspectives on Spatial Data Analysis*, edited by Luc Anselin and Sergio J Rey, 127–45. Berlin, Heidelberg: Springer Berlin Heidelberg.

*Geogr. Anal.*27 (4): 286–306.