What is Validity?
Validity is not a property of a test. It is the degree to which evidence and theory support the interpretations made of test scores for a specific proposed use. The same instrument can be valid for one decision and invalid for another, so validity is always stated in relation to a purpose.
The unitary view, and why it changed the question
Older writing treated validity as a set of separate types — content, criterion, construct — that an instrument could possess. The current professional standards treat it as a single concept supported by different sources of evidence: evidence based on test content, on response processes, on internal structure, on relations to other variables, and on the consequences of testing.
The practical effect is that 'is this test valid?' is not a well-formed question. 'What evidence supports using this test to decide X about this population?' is, and it is answerable.
What to ask for
Evidence for your use and your population, not a general claim. A test validated for graduate selection in one country is not thereby validated for frontline hiring in another, and translation is not validation.
Ask also about consequences. A procedure can predict adequately and still produce outcomes the organisation would not defend — which is why fairness evidence sits inside the validity argument rather than beside it.
Not the same as reliability
Reliability asks whether the measurement is consistent. Validity asks whether the conclusion drawn from it is justified. Reliability is necessary for validity and nowhere near sufficient.
ReliabilitySources
Related terms
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