04 — testing & measurement

Recall

Also written detection rate, coverage

Of all the real attacks in the corpus, the share the control caught. It is the number vendors quote, and on its own it means very little: recall is trivially maximised by flagging everything, and it is entirely a property of the corpus, so "95% detection" without the corpus is a statement about nothing. Recall is meaningful only paired with precision, on a named and preferably held-out set.

See also precision · held-out set · false negative

Related terms

Precision Testing & measurement
Of everything the control flagged, the share that was genuinely malicious — true positives divided by all positives.
Held-out set Testing & measurement
Test samples deliberately kept away from whoever is building the detection, so the score answers "does this generalise?" rather than "does this…
False negative Testing & measurement
A real attack the control failed to flag. False negatives and false positives trade off against each other: any threshold that reduces one increases the…

Testing & measurement

The words that decide whether a published detection number is evidence or decoration. Most vendor numbers in this space are quoted without any of them; see how we test for how these are applied in practice.

Recall is term 8 of 15 in this part of the glossary.

Held-out set Tune/test split Overfitting Baseline validation False positive False negative PrecisionRecallHard negative Detection vs prevention Model refusal Marginal value Red teaming Adversarial mutation Variance

This page is one entry from the agentic AI security glossary, which defines 60 terms in the same style. Where a term belongs to a published taxonomy or standard — the HackAgent attack families, the OWASP lists, AMTSO's guidelines, MITRE ATLAS, ISO/IEC 42001, the NIST AI RMF, the EU AI Act — the authoritative wording is the source document's, not ours, and specifics should be verified there. "Lethal trifecta" is Simon Willison's term. OWASP® is a trademark of the OWASP Foundation; ATT&CK® and ATLAS™ are trademarks of The MITRE Corporation. Naming a framework here is description, not a claim of certification or endorsement.