Measures of Diagnostic Accuracy
Sensitivity: the ability of a test to correctly classify an individual as having a disorder
True Positive
True Positive + False Negative
Specificity: the ability of a test to correctly identify a person as not having a disorder
True Negative
True Negative + False Positive
Positive predictive value (PPV): the probability that an individual has a disorder given a positive test result
True Positive
True Positive + False Positive
Negative predictive value (NPV): the probability that an individual does not have a disorder given a negative test result
True Negative
True Negative + False Negative
Likelihood ratio positive (LR+): the confidence that a positive score on a test came from a person who has the disorder rather than from a person who does not have the disorder sensitivity / (1 – specificity)
Likelihood ratio negative (LR-): the confidence that a negative score on a test came from a person who does not have the disorder rather than from a person who has the disorder (1 – sensitivity) / specificity
Diagnostic odds ratio (DOR): a means of comparing tests by putting results on the same scale (think effect size), the higher the DOR the better the test is at identifying the true status of individuals who have and do not have the disorder LR+/LR
