AI engineering glossary · Evaluation metrics
What is LR+ (likelihood ratio)?
Likelihood ratio (also called positive likelihood ratio, negative likelihood ratio, LR+): Metrics that say how much a test result shifts the odds of the condition. The positive ratio is sensitivity / (1 - specificity) and the negative ratio is (1 - sensitivity) / specificity. They do not depend on prevalence, so they transfer across populations.
Likelihood ratio: an example
With sensitivity 0.75 and specificity 0.99, the positive likelihood ratio is about 73, meaning a positive flag makes fraud about 73 times more likely in odds terms.
Related terms
More Evaluation metrics terms
- Log loss
- Macro averaging
- Matthews correlation coefficient
- MAUVE
- Max error
- Maximum calibration error
- McNemar's test
- Mean absolute error
Where you learn it
Likelihood ratio is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.