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Bibliographic Details
Main Authors: Borchers, Conrad, Baker, Ryan S.
Format: Preprint
Published: 2024
Subjects:
Online Access:https://arxiv.org/abs/2411.19090
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author Borchers, Conrad
Baker, Ryan S.
author_facet Borchers, Conrad
Baker, Ryan S.
contents Algorithmic bias continues to be a key concern of learning analytics. We study the statistical properties of the Absolute Between-ROC Area (ABROCA) metric. This fairness measure quantifies group-level differences in classifier performance through the absolute difference in ROC curves. ABROCA is particularly useful for detecting nuanced performance differences even when overall Area Under the ROC Curve (AUC) values are similar. We sample ABROCA under various conditions, including varying AUC differences and class distributions. We find that ABROCA distributions exhibit high skewness dependent on sample sizes, AUC differences, and class imbalance. When assessing whether a classifier is biased, this skewness inflates ABROCA values by chance, even when data is drawn (by simulation) from populations with equivalent ROC curves. These findings suggest that ABROCA requires careful interpretation given its distributional properties, especially when used to assess the degree of bias and when classes are imbalanced.
format Preprint
id arxiv_https___arxiv_org_abs_2411_19090
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle ABROCA Distributions For Algorithmic Bias Assessment: Considerations Around Interpretation
Borchers, Conrad
Baker, Ryan S.
Machine Learning
G.3
Algorithmic bias continues to be a key concern of learning analytics. We study the statistical properties of the Absolute Between-ROC Area (ABROCA) metric. This fairness measure quantifies group-level differences in classifier performance through the absolute difference in ROC curves. ABROCA is particularly useful for detecting nuanced performance differences even when overall Area Under the ROC Curve (AUC) values are similar. We sample ABROCA under various conditions, including varying AUC differences and class distributions. We find that ABROCA distributions exhibit high skewness dependent on sample sizes, AUC differences, and class imbalance. When assessing whether a classifier is biased, this skewness inflates ABROCA values by chance, even when data is drawn (by simulation) from populations with equivalent ROC curves. These findings suggest that ABROCA requires careful interpretation given its distributional properties, especially when used to assess the degree of bias and when classes are imbalanced.
title ABROCA Distributions For Algorithmic Bias Assessment: Considerations Around Interpretation
topic Machine Learning
G.3
url https://arxiv.org/abs/2411.19090