What does a positive value in Moran's Index indicate?

A positive value in Moran's Index indicates that similar values are clustered together, which demonstrates positive spatial autocorrelation. When the index is calculated, it measures the degree to which a spatial feature's value at one location is similar to the values at nearby locations. Thus, a positive Moran's Index suggests that high values are located near other high values, and low values are near other low values. This clustering can signify patterns in the data that might be influenced by underlying geographical or social phenomena.

In contrast, a negative value would indicate dissimilar values clustering, suggesting that high values are near low values, which reflects negative spatial autocorrelation. A value of zero would imply no spatial autocorrelation, meaning the values are distributed randomly across the space. Therefore, a positive Moran's Index distinctly highlights clustering of similar values, making it a significant metric in spatial statistics and geographic analysis.