Types of validity relevant to assessing “Truth”. From Felson. J Rheumatol 1993;20:531–4.
| Type of Validity | Meaning |
|---|---|
| Face | Credibility: Is the instrument credible? |
| Content | Comprehensiveness: Does the instrument (or group of instruments) sufficiently sample the core domain addressed? |
| Construct | Do the results of the instrument agree with expected results of other instruments measuring the same construct/concept? |
| Criterion | Difficult in this setting. The only external criterion available is longterm outcome. Does the result of the instrument predict or correlate with longterm outcome (e.g., death, disability, perhaps radiographic damage)? |