Which statement about the false positive rate is true?

Which statement about the false positive rate is true?

• A. The false positive rate equals the sensitivity
• B. The false positive rate equals the specificity
• C. The false positive rate equals 1 minus sensitivity
• D. The false positive rate equals 1 minus specificity

Answer: (D)

The false positive rate is about how often the test wrongly signals disease in people who don’t have it. It is the complement of specificity: specificity is the probability of a negative result when the disease is absent, so the false positive rate = 1 − specificity. For example, if the test correctly identifies 90% of healthy people as negative (specificity = 0.90), about 10% will be false positives (false positive rate = 0.10). This is different from sensitivity, which is about detecting disease in those who are diseased, and 1 minus sensitivity, which is the false negative rate.

The false positive rate is about how often the test wrongly signals disease in people who don’t have it. It is the complement of specificity: specificity is the probability of a negative result when the disease is absent, so the false positive rate = 1 − specificity. For example, if the test correctly identifies 90% of healthy people as negative (specificity = 0.90), about 10% will be false positives (false positive rate = 0.10). This is different from sensitivity, which is about detecting disease in those who are diseased, and 1 minus sensitivity, which is the false negative rate.