Which statement best describes specificity?

Which statement best describes specificity?

• A. Proportion of true positives correctly identified
• B. Proportion of true negatives correctly identified
• C. Proportion of false positives
• D. Proportion of false negatives

Answer: (B)

Specificity is the ability of a test to correctly identify people who do not have the condition. It is the true negative rate: the proportion of those without the condition who are correctly labeled negative, calculated as true negatives divided by the sum of true negatives and false positives. The statement describing the proportion of true negatives correctly identified best captures specificity. For contrast, identifying true positives correctly would be sensitivity, and the other options refer to false positives or false negatives. For example, if among healthy individuals the test labels 95 as negative and 5 as positive, specificity would be 95/100 = 0.95.

Specificity is the ability of a test to correctly identify people who do not have the condition. It is the true negative rate: the proportion of those without the condition who are correctly labeled negative, calculated as true negatives divided by the sum of true negatives and false positives. The statement describing the proportion of true negatives correctly identified best captures specificity. For contrast, identifying true positives correctly would be sensitivity, and the other options refer to false positives or false negatives. For example, if among healthy individuals the test labels 95 as negative and 5 as positive, specificity would be 95/100 = 0.95.