There's a reason it's called a confusion matrix!
This article has 345 citations: Sensitivity, Specificity, and Predictive Values: Foundations, Pliabilities, and Pitfalls in Research and Practice (2017, Frontiers in Public Health) —
ETA: Interestingly if you look at Wikipedia's talk page, there are plenty of comments about how this is often used incorrectly and blaming the terms. Eg
ETA2: I think from now on I'm going to write as "true positive rate (sensitivity)" and "true negative rate (specificity)".
This article has 345 citations: Sensitivity, Specificity, and Predictive Values: Foundations, Pliabilities, and Pitfalls in Research and Practice (2017, Frontiers in Public Health) —
The sensitivity of a screening test can be described in variety of ways, typically such as sensitivity being the ability of a screening test to detect a true positive, being based on the true positive rate, reflecting a test’s ability to correctly identify all people who have a condition, or, if 100%, identifying all people with a condition of interest by those people testing positive on the test.
The specificity of a test is defined in a variety of ways, typically such as specificity being the ability of a screening test to detect a true negative, being based on the true negative rate, correctly identifying people who do not have a condition, or, if 100%, identifying all patients who do not have the condition of interest by those people testing negative on the test.
ETA: Interestingly if you look at Wikipedia's talk page, there are plenty of comments about how this is often used incorrectly and blaming the terms. Eg
In the year since I posted this, and continued my phd research in bioinformatics, it's definitely apparent to me that there's no consensus in the community on what the formula for specificity should be, though my impression is still that the most common usage of specificity in the literature is as a synonym for positive predictive value. It's probably just the case of a wrong usage in the past propagating forward, since you must use the same evaluation metrics to compare your own results with previous ones, so I'm not pushing for this page to be changed in any way. I think it's an interesting anomaly, though.
IMHO: 'sensitivity' and 'specificity' are both VERY BAD 'misnomers' that serve confusion rather then clarity. The more accurate description of each would be 'True-Positive-Rate', 'True-Neg-Rate' respectively; alas, the terms 'sensitivity' and 'specificity' seem poor colloquials that have long served to confuse and mislead. Too bad that they now seem to be convention, but perhaps someone with clout and commitment should no less clarify this ambiguity.
ETA2: I think from now on I'm going to write as "true positive rate (sensitivity)" and "true negative rate (specificity)".
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