Table 2.

Glossary of terms used to describe psychometric and clinimetric properties of pain assessment tools.

Concept	Definition
Validity	The degree to which an instrument measures what it is intended to measure (Polit and Hungler, 1991).
Concurrent validity	The degree to which scores on an instrument are correlated with some external criterion, measured at the same time (Polit and Hungler, 1991).
Discriminant validity	An approach to construct validation that involves assessing the degree to which a single method of measuring two constructs yields different results (i.e., discriminates the two; Polit and Hungler, 1991).
Predictive validity	The degree to which an instrument can predict some criterion observed at a future time (Polit and Hungler, 1991).
Reliability	The degree of consistency or dependability (i.e., repeatability) with which an instrument measures the attribute it is designed to measure.
Interrater reliability	The degree to which two raters or observers, operating independently, assign the same ratings or values for an attribute being measured (Polit and Hungler, 1991).
Test-retest reliability	A procedure used to determine the stability of measurements over time (Waltz et al., 1991).
Internal consistency	The degree to which two or more measures are essentially measuring the same construct (Portney and Mary, 2009).
Sensitivity (SE)	Probability that a test result will be positive when the disease is present (true positive rate; Altman et al., 2000).
Specificity (SP)	Probability that a test result will be negative when the disease is not present (true negative rate; Altman et al., 2000).
Accuracy	Overall probability that a patient will be correctly classified (Altman et al., 2000).
Clinical utility	The usefulness of the measure for decision making (van Herk et al., 2007).
Clinical Utility Index (CUI)	The overall value of a test for combined screening and case finding (Mitchell, 2010).