A Class of Two-Group Polarization Measures

The phenomenon of income polarization is generally associated with a disappearing middle class but there does not seem to be a generally accepted definition of this notion. We characterize classes of polarization quasi-orderings and polarization measures in a framework where there are two income groups separated by the median. The axioms we employ are variants of within-group clustering and between-group spread properties, and an independence property. Furthermore, we illustrate that attempts to extend the axioms to more general settings severely restrict their appeal and conclude that alternative approaches may be required to capture concepts involving polarization. Copyright © 2008 Wiley Periodicals, Inc..