Ability of a test to detect specific features at all levels of magnitude or prevalence. Mathematically, sensitivity can be calculated by dividing the number of true positives by the sum of true positives and false negatives. In PDD testing this term is used to describe how well a test identifies a person engaging in deception to the issue under investigation. It is a measure of “true positive” results generally expressed as a decimal (for example a sensitivity of 0.90 would indicate a particular test identified 90% of the liars.)