Definition
Plain language
A score from zero to one for how well a classifier separates the right answers from the wrong ones.
As stated in the literature
Area Under the Receiver Operating Characteristic curve, a threshold-free measure of binary classification quality; a value of 1.0 indicates perfect separation.
Also called: AUC
Why it matters: It summarizes classifier quality in a single number that doesn't depend on a particular operating point, making models easy to compare.
For example, a spam filter with AUROC 0.95 ranks almost all spam messages above almost all real ones, regardless of where you draw the threshold.
Heard on the show
“The AUROC drops by less than one one-thousandth.”Episode 037 — Why Hallucination Detectors Miss Stale Facts: A Geometric Story About What Models Know But Don't Say