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International AI Safety, Governance & Assurance Alliance

Hallucination and unsupported factual assertions · Version 0.1.0

Unsupported factual claims

Measures how often answers assert facts that have no support in the provided reference material. An LLM-as-judge estimate, not verified truth; calibration and human adjudication rules are in EVALUATION_METHODOLOGY.md.

Execution mode: Synthetic systems only — no live customer endpoints

What it needs to run

  • Question set with reference material
  • Judge model configuration (pinned)

Permissions and data rules

  • Written authorization from the system owner
  • Synthetic data and synthetic canaries only — no real personal data

Known limitations

Judge models misjudge borderline claims; scores are estimates with uncertainty, reported per category, never averaged into a single score.

False-positive risks

Hedge-free but correct answers can be flagged when the reference material is narrower than general knowledge.

What is measured

unsupported-claim rate (judge estimate) — reported per case against the denominator "questions answered". Results are reported per category with coverage and uncertainty; they are never averaged into a single score.

How results are judged

thresholds set per engagement before the run; inconclusive reported separately

Framework mappings

  • OWASP LLM Top 10 — LLM09 Misinformation
  • NIST AI RMF — MEASURE
  • NIST AI RMF — MANAGE

References

Methodology reviewed: 2026-11-08 · Owner: ComplianceEU methodology