What best defines an intervening variable in research?

• A. A hypothetical variable used to explain causal links between other variables and that cannot be observed in an experiment.
• B. A variable that directly causes changes in the dependent variable and is easily observed.
• C. A variable that measures the outcome of the study after data collection.
• D. A fixed characteristic of the population that remains constant.

Answer: (A)

An intervening variable (often called a mediator) is a middle, hypothetical construct that explains how or why an independent variable affects a dependent variable. It represents the mechanism linking cause and effect, and because it reflects a process rather than a directly observable outcome, researchers usually infer it from patterns in the data and through mediation analyses.

This is why the best description is a hypothetical variable used to explain causal links between other variables and that cannot be observed in an experiment. It captures the process by which the cause influences the effect, rather than being the direct cause itself or the outcome measured at the end of the study, or a fixed characteristic of the population. For example, a program might improve well-being through increased coping skills; the coping skills act as the intervening variable explaining how the program leads to better outcomes.