Which statement distinguishes moderation from mediation?

• A. Moderation refers to a third variable that changes the strength of the relationship; mediation refers to a variable that explains the pathway.
• B. Moderation explains the pathway; mediation changes the strength of the relationship.
• C. Both describe the same concept.
• D. Neither has to do with third variables.

Answer: (A)

The essential idea here is how a third variable can relate to the main relationship: as a moderator, it changes how strong the relationship is; as a mediator, it explains the path through which the relationship operates.

A moderator affects the strength or direction of the IV–DV link. In practice, the effect of the independent variable on the dependent variable depends on the level of the moderator. You’d see an interaction: the same IV has different effects at different levels of the moderator. For example, stress might reduce work performance more when sleep is low, but the effect is smaller when sleep is high.

A mediator, on the other hand, explains the mechanism or process by which the IV influences the DV. The influence passes through the mediator: the IV affects the mediator, which then affects the DV, creating an indirect pathway. For instance, social support might boost well-being because it increases self-esteem, which in turn raises well-being.

The statement aligned with these distinctions says moderation involves a variable that changes the strength of the relationship, while mediation involves a variable that explains the pathway. The other options mix up the roles or claim there’s no difference, which doesn’t fit how these concepts are used in analysis.