Table 1

Types of validity evidence

Type of validity evidenceWhat is it?
FaceA judgement that, on the face of it, the test is likely to measure the intended construct13 14
ContentA judgement that the test adequately represents the construct of interest. COSMIN requires a judgement about relevance and comprehensiveness of the item13 14
CriterionThe extent to which test scores correlate with scores on a ‘gold standard’ test of the same construct. Not applicable to PROMs of constructs for which no ‘gold standard’ test exists. COSMIN considers that the term criterion validity in testing of PROMs applies only when testing a short-form version of a PROM against the original version14
PredictiveThe extent to which test scores accurately predict a future outcome13
Construct validityThe extent to which the test measures the intended construct and the inferences that can therefore be made from the scores13
 ConvergentThe extent to which test scores correlate with scores on another (concurrently administered) test of the same construct13
 DiscriminantThe extent to which test scores do not correlate with scores on another (concurrently administered) test of a different construct13
 Known or extreme groupsThe extent to which test scores differ between groups of persons known or expected to differ on the variable of interest13
Responsiveness (longitudinal validity)The extent to which change in test scores reflects change in the construct13 14
StructuralIn the COSMIN terminology, this refers to the examination of the extent to which all the items in a PROM reflect a single construct (unidimensionality), or the extent to which sub-scales can be demonstrated (multidimensionality)14
Cross-cultural validationThe process of translation and retesting the measurement properties of a test in another language/cultural setting14
  • COSMIN, consensus-based standards for the selection of health-status measurement instruments; PROM, patient-reported outcome measures.