The question of whether a measure that is devised for a concept really does reflect the concept that it is supposed to be denoting relates to

Whether a measure devised for a concept truly reflects that concept is the question of measurement validity.

Measurement validity, also called construct validity, links the indicator to the concept it stands for.

Ecological validity instead asks whether findings apply to natural, everyday settings.

Internal validity asks whether the causal inference within a study is sound.

External validity asks whether results generalize to other people and contexts.

A measure can be reliable yet still lack validity if it consistently measures the wrong thing.