Exploring and Correcting the Bias in the Estimation of the Gini Measure of Inequality

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Bibliographic Details
Title: Exploring and Correcting the Bias in the Estimation of the Gini Measure of Inequality
Language: English
Authors: Juan F. Muñoz (ORCID 0000-0001-7427-6630), Pablo J. Moya-Fernández (ORCID 0000-0003-0980-3849), Encarnación Álvarez-Verdejo (ORCID 0000-0002-0473-6037)
Source: Sociological Methods & Research. 2025 54(1):237-274.
Availability: SAGE Publications. 2455 Teller Road, Thousand Oaks, CA 91320. Tel: 800-818-7243; Tel: 805-499-9774; Fax: 800-583-2665; e-mail: journals@sagepub.com; Web site: https://sagepub.com
Peer Reviewed: Y
Page Count: 38
Publication Date: 2025
Document Type: Journal Articles
Reports - Evaluative
Descriptors: Bias, Educational Indicators, Equal Education, Monte Carlo Methods, Sampling, Statistical Inference, Income
DOI: 10.1177/00491241231176847
ISSN: 0049-1241
1552-8294
Abstract: The Gini index is probably the most commonly used indicator to measure inequality. For continuous distributions, the Gini index can be computed using several equivalent formulations. However, this is not the case with discrete distributions, where controversy remains regarding the expression to be used to estimate the Gini index. We attempt to bring a better understanding of the underlying problem by regrouping and classifying the most common estimators of the Gini index proposed in both infinite and finite populations, and focusing on the biases. We use Monte Carlo simulation studies to analyse the bias of the various estimators under a wide range of scenarios. Extremely large biases are observed in heavy-tailed distributions with high Gini indices, and bias corrections are recommended in this situation. We propose the use of some (new and traditional) bootstrap-based and jackknife-based strategies to mitigate this bias problem. Results are based on continuous distributions often used in the modelling of income distributions. We describe a simulation-based criterion for deciding when to use bias corrections. Various real data sets are used to illustrate the practical application of the suggested bias corrected procedures.
Abstractor: As Provided
Entry Date: 2025
Accession Number: EJ1457727
Database: ERIC
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Abstract:The Gini index is probably the most commonly used indicator to measure inequality. For continuous distributions, the Gini index can be computed using several equivalent formulations. However, this is not the case with discrete distributions, where controversy remains regarding the expression to be used to estimate the Gini index. We attempt to bring a better understanding of the underlying problem by regrouping and classifying the most common estimators of the Gini index proposed in both infinite and finite populations, and focusing on the biases. We use Monte Carlo simulation studies to analyse the bias of the various estimators under a wide range of scenarios. Extremely large biases are observed in heavy-tailed distributions with high Gini indices, and bias corrections are recommended in this situation. We propose the use of some (new and traditional) bootstrap-based and jackknife-based strategies to mitigate this bias problem. Results are based on continuous distributions often used in the modelling of income distributions. We describe a simulation-based criterion for deciding when to use bias corrections. Various real data sets are used to illustrate the practical application of the suggested bias corrected procedures.
ISSN:0049-1241
1552-8294
DOI:10.1177/00491241231176847