Measuring inequality in a cross-tabulation with ordered categories: From the Gini coefficient to the Tog coefficient

Abstract

This paper introduces the Tog coefficient, which can be used to measure the level of inequality in a cross-tabulation of two ordinal-level variables. The Gini coefficient is a standard measure of income inequality which has been adapted by other authors for use in different contexts such as the measurement of health inequalities and the quantification of occupational segregation; the Tog coefficient represents a further stage in this process of development. The paper outlines the construction of the Tog coefficient and illustrates this using a social mobility table based on data from the 1972 Oxford Mobility Study. The trend in social mobility-related inequality as measured by the Tog coefficient is compared with the findings of Goldthorpe et al. based on odds ratios. A more elaborate application of the Tog coefficient uses a variety of data relating to the similarity of spouses' class backgrounds to demonstrate the existence of a long-term decline in the level of inequality in British society.