07 · Measuring Models
Hallucination
Confident fabrication
A confident-seeming model output that is unsupported or false, such as an invented citation or incorrect figure. Generation alone does not verify claims; grounding, retrieval, tools, and independent checks can reduce risk but not guarantee truth.
Concrete example
Asked for a source, a model may produce a perfectly formatted citation to a paper that was never written.
Why it matters
The reason anything decision-relevant needs independent verification. Full stop.