Identifying, measuring, and mitigating individual unfairness for supervised learning models and application to credit risk models

TL;DR

This paper presents a flexible two-step method for identifying and mitigating individual unfairness in credit risk models, using a learned similarity metric and evaluating fairness improvements through experiments.

Contribution

It introduces a novel two-step training process that learns a fair similarity metric and applies it to improve individual fairness in credit models, adaptable with various fairness algorithms.

Findings

The two-step method effectively reduces individual unfairness.

The learned similarity metric correlates with fairness improvements.

Experimental results demonstrate the approach's effectiveness.

Abstract

In the past few years, Artificial Intelligence (AI) has garnered attention from various industries including financial services (FS). AI has made a positive impact in financial services by enhancing productivity and improving risk management. While AI can offer efficient solutions, it has the potential to bring unintended consequences. One such consequence is the pronounced effect of AI-related unfairness and attendant fairness-related harms. These fairness-related harms could involve differential treatment of individuals; for example, unfairly denying a loan to certain individuals or groups of individuals. In this paper, we focus on identifying and mitigating individual unfairness and leveraging some of the recently published techniques in this domain, especially as applicable to the credit adjudication use case. We also investigate the extent to which techniques for achieving individual fairness are effective at achieving group fairness. Our main contribution in this work is functionalizing a two-step training process which involves learning a fair similarity metric from a group sense using a small portion of the raw data and training an individually "fair" classifier using the rest of the data where the sensitive features are excluded. The key characteristic of this two-step technique is related to its flexibility, i.e., the fair metric obtained in the first step can be used with any other individual fairness algorithms in the second step. Furthermore, we developed a second metric (distinct from the fair similarity metric) to determine how fairly a model is treating similar individuals. We use this metric to compare a "fair" model against its baseline model in terms of their individual fairness value. Finally, some experimental results corresponding to the individual unfairness mitigation techniques are presented.