Negative Predictive Value (NPV)

Evidence-Based Medicine

An easy way to understand NPV is to dissect the name. In Negative Predictive Value, we are looking at how good a Negative test is at predicting Negative disease (ie. that the person doesn’t have a disease). The negative predictive value of a test is the...

Positive Predictive Value (PPV)

Evidence-Based Medicine

An easy way to understand PPV is to dissect the name. In Positive Predictive Value, we are looking at how good a positive test is at predicting that a person actually has a disease. Positive predictive value refers to the percentage of patients with a positive test...

Specificity (Sp)

Evidence-Based Medicine

Specificity (Sp) The percentage of patients without a disorder who have a negative test for that disorder is a test’s specificity. True negative rate. The ability to detect health (nondisease). Sp is the probability that among people who don’t have the disease,...

Sensitivity (Sn)

Evidence-Based Medicine

The percentage of patients with a disorder who have a positive test for that disorder is a test’s sensitivity. Sensitivity is the True positive rate. The ability to detect disease. In other words, among patients with a disease, sensitivity is the probability that the...