The degree to which the measure of a concept truly reflects that concept refers to:

Measurement validity is the degree to which a measure of a concept truly reflects that concept.

It asks whether the indicator captures what it claims to capture.

Ecological fallacy is the error of inferring individual traits from group-level data.

Ecological validity concerns whether findings apply to natural everyday settings.

External validity concerns generalisation of results beyond the study.

Measurement validity presupposes reliability, though reliability alone is not enough.