Label proxy markets plainly

Usage-share, passenger, prescription, or revenue proxies should be named as proxies before readers infer legal conclusions.

Source records3report custody

Linked markets3analytical context

Research themes2publication taxonomy

Evidence needs4future verification inputs

Recommendation evidence chain

The source boundary stays visible from analysis to proposed action.

02Evidence custody3 sources / 3 marketsLinked context, not independent endorsement

03Normative recommendationAR-PA-006Measurement & scope

04Implementation evidenceNot assessedNo adoption or impact inference

Source report position

HHI should be a public-reading tool: useful for triage, but only credible when paired with market definition, source coverage, and caveats.

Intended audience: Agency staff, journalists, and civic researchers
Policy priority: Foundation
Instrument: Measurement & scope
Publication: AR-MM-2026-01 / version 1.0
Canonical citation: Antitrust Radar Research Team. (2026, May 16). How HHI Helps Explain Market Concentration: A public primer for reading concentration dashboards. Methods and Measures, AR-MM-2026-01 (Version 1.0). Antitrust Radar. https://antitrustradar.org/reports/hhi-primer

Evidence still needed