Equalised Odds is not Equal Individual Odds: Post-processing for Group and Individual Fairness

Fuente: arXiv
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Autores principales: Small, Edward A., Sokol, Kacper, Manning, Daniel, Salim, Flora D., Chan, Jeffrey
Formato: Preprint
Publicado: 2023
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author Small, Edward A.
Sokol, Kacper
Manning, Daniel
Salim, Flora D.
Chan, Jeffrey
author_facet Small, Edward A.
Sokol, Kacper
Manning, Daniel
Salim, Flora D.
Chan, Jeffrey
contents Group fairness is achieved by equalising prediction distributions between protected sub-populations; individual fairness requires treating similar individuals alike. These two objectives, however, are incompatible when a scoring model is calibrated through discontinuous probability functions, where individuals can be randomly assigned an outcome determined by a fixed probability. This procedure may provide two similar individuals from the same protected group with classification odds that are disparately different -- a clear violation of individual fairness. Assigning unique odds to each protected sub-population may also prevent members of one sub-population from ever receiving equal chances of a positive outcome to another, which we argue is another type of unfairness called individual odds. We reconcile all this by constructing continuous probability functions between group thresholds that are constrained by their Lipschitz constant. Our solution preserves the model's predictive power, individual fairness and robustness while ensuring group fairness.
format Preprint
id arxiv_https___arxiv_org_abs_2304_09779
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Equalised Odds is not Equal Individual Odds: Post-processing for Group and Individual Fairness
Small, Edward A.
Sokol, Kacper
Manning, Daniel
Salim, Flora D.
Chan, Jeffrey
Machine Learning
Computers and Society
Optimization and Control
Probability
Group fairness is achieved by equalising prediction distributions between protected sub-populations; individual fairness requires treating similar individuals alike. These two objectives, however, are incompatible when a scoring model is calibrated through discontinuous probability functions, where individuals can be randomly assigned an outcome determined by a fixed probability. This procedure may provide two similar individuals from the same protected group with classification odds that are disparately different -- a clear violation of individual fairness. Assigning unique odds to each protected sub-population may also prevent members of one sub-population from ever receiving equal chances of a positive outcome to another, which we argue is another type of unfairness called individual odds. We reconcile all this by constructing continuous probability functions between group thresholds that are constrained by their Lipschitz constant. Our solution preserves the model's predictive power, individual fairness and robustness while ensuring group fairness.
title Equalised Odds is not Equal Individual Odds: Post-processing for Group and Individual Fairness
topic Machine Learning
Computers and Society
Optimization and Control
Probability
url https://arxiv.org/abs/2304.09779