The extent to which an instrument measures a characteristic that cannot be directly observed but is assumed to exist is

Construct validity is the extent to which an instrument measures an unobservable characteristic assumed to exist.

Face validity only judges whether a test appears relevant on its surface.

Criterion validity checks agreement with an external outcome or standard.

Content validity examines whether items cover the full domain of the concept.

Constructs like intelligence or anxiety cannot be seen directly, only inferred.

It is tested through convergent and discriminant evidence.