---
title: "Adverse-impact ratio (AIR)"
description: "The selection rate of a group divided by the selection rate of the most-selected group."
canonical: https://aigovernanceengineer.com/glossary/adverse-impact-ratio-air
author: "Jorge García Aibar"
license: "CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)"
doi: https://doi.org/10.5281/zenodo.22956197
version: "0.5.0"
updated: 2026-09-24
---

# Adverse-impact ratio (AIR)

The selection rate of a group divided by the selection rate of the most-selected group. Under the US Uniform Guidelines a ratio below four-fifths is generally treated as evidence of adverse impact [1]; engineering practice reads it as a trigger for investigation, reported with counts and a confidence interval.

- Developed in: [ch. 16, The four-fifths rule and the adverse-impact ratio](https://aigovernanceengineer.com/bok/fairness-and-explainability#the-four-fifths-rule-and-the-adverse-impact-ratio)
- Chapters: [ch. 16, Fairness & XAI](https://aigovernanceengineer.com/bok/fairness-and-explainability)
- In the glossary chapter: https://aigovernanceengineer.com/bok/glossary#t-adverse-impact-ratio-air

## Sources

[1] 29 CFR 1607.4(D), Uniform Guidelines on Employee Selection Procedures (1978) (adverse impact and the "four-fifths rule", with statistical-significance and small-numbers caveats; text as of 2026-09-01). eCFR. 2026-09-01. https://www.ecfr.gov/current/title-29/subtitle-B/chapter-XIV/part-1607/section-1607.4 (verified: primary)