Journal of Classification

, Volume 35, Issue 3, pp 580–586 | Cite as

On the Negative Bias of the Gini Coefficient due to Grouping

  • Matthijs J. Warrens
Open Access


The Gini coefficient is a measure of statistical dispersion that is commonly used as a measure of inequality of income, wealth or opportunity. Empirical research has shown that the coefficient may have a nonnegligible downward bias when data are grouped. It is unknown under which grouping conditions the downward bias occurs. In this note it is shown that the Gini coefficient strictly decreases if the data are partitioned into equal sized groups.


Statistical dispersion Measure of inequality Inequality of income Inequality of wealth Grouping data 


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© The Author(s) 2018

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Authors and Affiliations

  1. 1.University of GroningenGroningenThe Netherlands

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