On measuring segregation in samples with small units

Standard indexes of segregation measure a sample’s distance from evenness, which occurs when each sample unit (e.g., an occupation) has the population share of both the minority and majority groups. We show that random allocation of individuals to units generates substantial unevenness among small units and hence that standard segregation indexes reflect random allocation as well as systematic group segregation. We then modify two popular indexes so that they measure deviations from random allocation rather than deviations from evenness. An empirical example suggests that these modified indexes provide improved measures of the systematic component of group segregation.