While the field of measuring vertical inequality (VI, i.e. inequality among individuals in a society) is well developed and sophisticated, much less attention has been paid to measuring horizontal inequalities (HI), or inequalities among groups in a society. This paper proposes ways of measuring and monitoring horizontal inequalities.
After an introduction, the paper briefly discusses why and when group inequalities matter. Section 3 considers problems in categorising groups, selecting dimensions of HIs and finding data. In measuring societal HIs for a society three issues need to be considered: first, how to aggregate inequalities across groups when there are more than two groups; secondly, how to take the whole distribution of variables of interest of each group into account, rather than compare the means alone; and thirdly, whether (and how) to arrive at a multidimensional index or indices of HIs. Section 4 considers problems in arriving at aggregate measures of HIs in a society where there are multiple groups and Section 5 discusses how the whole distribution might be taken into account in estimating HIs. Both propose specific measures and illustrate these empirically. Section 6 briefly discusses the question of multidimensional indices for HIs. Finally, Section 7 presents conclusions.
Oxford, UK: Centre for Research on Inequality, Human Security and Ethnicity (CRISE). CRISE Overview No. 4, 46 pp.