If a conclusion incorporates a causal relationship between two or more variables, it has measured:

A conclusion that captures a causal relationship between two or more variables has demonstrated internal validity.

External validity concerns generalising findings beyond the study.

Replicability is whether the study yields the same results when repeated.

Conceptualisation is defining abstract concepts before measurement.

Ruling out confounding variables is essential to any claim of causation.

Randomised experiments provide the strongest basis for internal validity.