Spatial Exposure Index

The exposure and isolation indices, written P*, measure residential segregation as the degree of potential contact between population groups across the neighbourhoods of a region. Developed by Wendell Bell in 1954 and later codified by Massey and Denton in 1988 as the 'exposure' dimension of segregation, they answer a different question from evenness measures like the dissimilarity index: not how unevenly groups are distributed, but how much members of one group actually share neighbourhoods with members of another or only with their own. The interaction index gauges cross-group exposure while the isolation index gauges within-group concentration, each interpretable as a probability.