Measuring local segregation in Northern Ireland

Segregation measures have been applied in the study of many societies and traditionally such measures have been used to assess the degree of division between social and cultural groups across national or regional areas. The degree of segregation can vary substantially from place to place even within cities. In this paper, the concern is with religious/political segregation – particularly the proportion of Protestants (often taken as an indicator of Unionism) to Catholics (often taken as an indicator of Nationalism). This paper examines a variety of global measures and also local measures that account for spatial variation in segregation. The dissimilarity index D is one widely used measure and this can be adapted to account for spatial variation. Wong (2003) discusses a range of spatial segregation measures including a variant of the D index. In the present paper, global and local (spatial) variants of D and other indices are computed based on the religious/political composition of Northern Ireland with 2001 census Output Areas as the measurement unit. The paper demonstrates (i) the high degree of spatial variation in segregation in Northern Ireland and (ii) compares results obtained using a variety of global and local measures of segregation.