Specificity
Specificity is the true negative rate: the probability a test is negative given the condition is false.
Definition
Specificity is a conditional probability: P(test negative given condition false). It is also called the true negative rate.
Why it matters
Specificity and sensitivity can be translated into likelihood ratios used to update beliefs via Bayes theorem. High specificity reduces the false positive rate.
How it connects
• False positive rate equals 1 minus specificity.
• Specificity contributes to LR plus and LR minus when combined with sensitivity.
Common pitfalls
Assuming high specificity means high certainty: Base rates still matter.