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Sensitivity and specificity
GUEST EDITORIAL
Sensitivity and Specificity Sensitivity is the ability to sense, or “to detect.” Specificity is the capacity to specify, that is “to name or state explicitly.” (The quotes are from Webster’sNew Collegiate Dictionary.) Many who use decision matrix in determining the accuracy of diagnostic examinations and tests refer to the true positive rate or fraction as the sensitivity of the procedure and true negative rate or fraction as the specificity. Applying sensitivity and specificity in this manner has been a poor use of the terms. To appreciate this discrepancy all one has to do is listen carefully to the manner in which sensitivity and specificity are used in any general medical disclosure on tests or examinations; that is, a discourse in which the two words are not deliberately related to decision matrix with true positive and true negative rate implications. In the common language of medicine the meanings of these terms are as defined in the dictionary. True positive and true negative rates are just that and nothing else. We do not usually call false positive “antisensitivity” and false negative “antispecificity”; such uses do not make sense. The misuses of sensitivity and specificity as synonyms for true positive and true negative rates have been confusing and have hindered the development of more valuable evaluation techniques. Many statisticians agree that these uses should be discontinued. Perhaps it would be wise to have the following definitions assigned to diagnostic procedures: sensitivity is the ability to detect abnormalities and specificity is the precision with which etiology can be stated explicitly. These would be more appropriate terms than detectability and classifiability, which I used in my article “Diagnosis through Imaging: Generation, Detection, and Classification.” Terminology can be crucial to the dissemination of an idea, which should be expressed in fitting language to facilitate understanding. Majic S. Potsaid, M.D.
Sensitivity and Specificity Sensitivity is the ability to sense, or “to detect.” Specificity is the capacity to specify, that is “to name or state explicitly.” (The quotes are from Webster’sNew Collegiate Dictionary.) Many who use decision matrix in determining the accuracy of diagnostic examinations and tests refer to the true positive rate or fraction as the sensitivity of the procedure and true negative rate or fraction as the specificity. Applying sensitivity and specificity in this manner has been a poor use of the terms. To appreciate this discrepancy all one has to do is listen carefully to the manner in which sensitivity and specificity are used in any general medical disclosure on tests or examinations; that is, a discourse in which the two words are not deliberately related to decision matrix with true positive and true negative rate implications. In the common language of medicine the meanings of these terms are as defined in the dictionary. True positive and true negative rates are just that and nothing else. We do not usually call false positive “antisensitivity” and false negative “antispecificity”; such uses do not make sense. The misuses of sensitivity and specificity as synonyms for true positive and true negative rates have been confusing and have hindered the development of more valuable evaluation techniques. Many statisticians agree that these uses should be discontinued. Perhaps it would be wise to have the following definitions assigned to diagnostic procedures: sensitivity is the ability to detect abnormalities and specificity is the precision with which etiology can be stated explicitly. These would be more appropriate terms than detectability and classifiability, which I used in my article “Diagnosis through Imaging: Generation, Detection, and Classification.” Terminology can be crucial to the dissemination of an idea, which should be expressed in fitting language to facilitate understanding. Majic S. Potsaid, M.D.