A PERIMETER-BASED CLUSTERING INDEX FOR MEASURING SPATIAL SEGREGATION - A COGNITIVE GIS APPROACH

Many efforts have been made to develop segregation indices that incorp orate spatial interaction based on the contiguity concept. Contiguity refers to how similar the concentration of the subject of interest in one areal unit is to that in adjacent areal units. However, highly seg regated situations are typically considered to be isolated sections or enclaves rather than smoothly formed peaks of concentration in space. Therefore, highly segregated enclaves may not exhibit contiguity. In this paper, a new index to measure the degree of clustering is develop ed and it is compared with the existing indices of concentration or se gregation. The proposed clustering index (I-c) tends to give more weig ht to 'enclaveness' rather than contiguity alone. This may be a good p roperty for those cases in which the primary concern of an investigato r is the formation of enclaves of a socioeconomic subject, including m inority populations, poverty, crime, epidemics, and mortgage red-linin g. Additionally, its property of robustness to the citywide rate allow s us to perform properly an intercity comparison of a given subject by index score even when the citywide rate varies significantly, unlike the other measures.