How to measure segregation in the education system?

Summary The measurement of segregation consists in quantifying a state of separation of people belonging to different groups (social, ethnic, etc.) in a given territory. Its opposite is the more positive measure of social mix. Measuring segregation, particularly between schools, is a major challenge for the analysis and management of the education system. This article reviews the general principles of indicators for measuring segregation, and discusses the properties of the main indices usually used. We use one of these indicators, the normalized entropy index, to propose diagnostic elements on social segregation between French secondary schools, based on data from the Scolarité information system. These elements make it possible, first of all, to characterize the territories according to a greater or lesser degree of segregation between the colleges: we highlight a stronger segregation in the academies and in the urban departments. The standardized entropy index, because of its decomposability property, makes it possible to highlight different segregation mechanisms according to social groups and to evaluate the importance of the educational sector in segregation.