On the Relationship Between the Gini Coefficient and Skewness

ABSTRACT Skewness, a measure of the asymmetry of a distribution, is frequently employed to reflect a biologically important property. Another statistic, the Gini coefficient (GC), originally used to measure economic inequality, has been validated in measuring the inequality of biological size distri...

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Main Authors: Meng Lian, Long Chen, Cang Hui, Fuyuan Zhu, Peijian Shi
Format: Article
Language:English
Published: Wiley 2024-12-01
Series:Ecology and Evolution
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Online Access:https://doi.org/10.1002/ece3.70637
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author Meng Lian
Long Chen
Cang Hui
Fuyuan Zhu
Peijian Shi
author_facet Meng Lian
Long Chen
Cang Hui
Fuyuan Zhu
Peijian Shi
author_sort Meng Lian
collection DOAJ
description ABSTRACT Skewness, a measure of the asymmetry of a distribution, is frequently employed to reflect a biologically important property. Another statistic, the Gini coefficient (GC), originally used to measure economic inequality, has been validated in measuring the inequality of biological size distributions. Given that the GC and skewness control overlapping domains and interact with each other, researchers are perplexed by their relationship (varying with the biological [organ, tissue or cell] size distributions) and use both of them together to provide a more complete picture of the data. This study provides analytical forms of the GC for biological size distributions, including two‐parameter Weibull, uniform, normal, two‐parameter lognormal, gamma, three‐parameter Weibull, three‐parameter lognormal, and three‐parameter gamma distributions. Two empirical data sets and simulation data sets were used to clarify the GC–skewness relationships under different distributions. For the aforementioned distributions, the GC–skewness relationships can be divided into three types: (i) for a symmetrical distribution, the skewness is 0, and the GC ranges from 0.56 to 0.58 multiplied by the standard deviation divided by the mean irrespective of its relationship with the skewness; (ii) for an asymmetric distribution with a zero threshold, the GC is a monotonously increasing function of the skewness, and the two measures are equivalent; (iii) for an asymmetric distribution with a non‐zero threshold, the GC is determined by the skewness and an additional correction factor. We showed the differences in improving the accuracy of GC calculations based on small‐sample adjustments among various calculation methods, including the polygon (trapezoidal set) area method and the rotated Lorenz curve method. The present study turns the GC into a property of the distribution and offers a clear understanding for the GC–skewness relationship. This work provides insights into selecting and using the GC to measure inequality in ecological data, facilitating more accurate and meaningful analyses.
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spelling doaj-art-b8ddb714fc7f4e91bf799a26cbd2e1f32025-08-20T02:00:47ZengWileyEcology and Evolution2045-77582024-12-011412n/an/a10.1002/ece3.70637On the Relationship Between the Gini Coefficient and SkewnessMeng Lian0Long Chen1Cang Hui2Fuyuan Zhu3Peijian Shi4Co‐Innovation Centre for Sustainable Forestry in Southern China, State Key Laboratory of Tree Genetics and Breeding, Bamboo Research Institute, College of Life Sciences Nanjing Forestry University Nanjing ChinaCo‐Innovation Centre for Sustainable Forestry in Southern China, State Key Laboratory of Tree Genetics and Breeding, Bamboo Research Institute, College of Life Sciences Nanjing Forestry University Nanjing ChinaDepartment of Mathematical Sciences, Centre for Invasion Biology Stellenbosch University Stellenbosch South AfricaCo‐Innovation Centre for Sustainable Forestry in Southern China, State Key Laboratory of Tree Genetics and Breeding, Bamboo Research Institute, College of Life Sciences Nanjing Forestry University Nanjing ChinaCo‐Innovation Centre for Sustainable Forestry in Southern China, State Key Laboratory of Tree Genetics and Breeding, Bamboo Research Institute, College of Life Sciences Nanjing Forestry University Nanjing ChinaABSTRACT Skewness, a measure of the asymmetry of a distribution, is frequently employed to reflect a biologically important property. Another statistic, the Gini coefficient (GC), originally used to measure economic inequality, has been validated in measuring the inequality of biological size distributions. Given that the GC and skewness control overlapping domains and interact with each other, researchers are perplexed by their relationship (varying with the biological [organ, tissue or cell] size distributions) and use both of them together to provide a more complete picture of the data. This study provides analytical forms of the GC for biological size distributions, including two‐parameter Weibull, uniform, normal, two‐parameter lognormal, gamma, three‐parameter Weibull, three‐parameter lognormal, and three‐parameter gamma distributions. Two empirical data sets and simulation data sets were used to clarify the GC–skewness relationships under different distributions. For the aforementioned distributions, the GC–skewness relationships can be divided into three types: (i) for a symmetrical distribution, the skewness is 0, and the GC ranges from 0.56 to 0.58 multiplied by the standard deviation divided by the mean irrespective of its relationship with the skewness; (ii) for an asymmetric distribution with a zero threshold, the GC is a monotonously increasing function of the skewness, and the two measures are equivalent; (iii) for an asymmetric distribution with a non‐zero threshold, the GC is determined by the skewness and an additional correction factor. We showed the differences in improving the accuracy of GC calculations based on small‐sample adjustments among various calculation methods, including the polygon (trapezoidal set) area method and the rotated Lorenz curve method. The present study turns the GC into a property of the distribution and offers a clear understanding for the GC–skewness relationship. This work provides insights into selecting and using the GC to measure inequality in ecological data, facilitating more accurate and meaningful analyses.https://doi.org/10.1002/ece3.70637adjusted Gini coefficientdiameter at breast heightskewnessWeibull distribution
spellingShingle Meng Lian
Long Chen
Cang Hui
Fuyuan Zhu
Peijian Shi
On the Relationship Between the Gini Coefficient and Skewness
Ecology and Evolution
adjusted Gini coefficient
diameter at breast height
skewness
Weibull distribution
title On the Relationship Between the Gini Coefficient and Skewness
title_full On the Relationship Between the Gini Coefficient and Skewness
title_fullStr On the Relationship Between the Gini Coefficient and Skewness
title_full_unstemmed On the Relationship Between the Gini Coefficient and Skewness
title_short On the Relationship Between the Gini Coefficient and Skewness
title_sort on the relationship between the gini coefficient and skewness
topic adjusted Gini coefficient
diameter at breast height
skewness
Weibull distribution
url https://doi.org/10.1002/ece3.70637
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