False Positive Rate
False positive rate is the probability of a positive test when the condition is false, equal to 1 minus specificity.
Definition
False positive rate is P(test positive given condition false). It equals 1 minus specificity.
Why it matters
False positives can dominate when base rates are low. Even a good test can produce many false positives if the base rate of the condition is small.
How it connects
• A lower false positive rate generally increases evidence strength for a positive result.
• It feeds into likelihood ratio calculations used in Bayes updates.
Common pitfalls
Ignoring base rates: Low base rate means most positives can still be false.