Which statement best captures the difference between mediation and moderation?

Which statement best captures the difference between mediation and moderation?

• A. Mediation refers to X predicting Y through M; Moderation refers to X predicting Y only for a particular M group.
• B. Mediation is about group differences; Moderation is about an indirect path.
• C. Moderation implies an indirect path; Mediation is a boundary condition.
• D. They are the same concept.

Answer: (A)

The key idea is to distinguish mechanism from conditional effect. Mediation explains how or why X influences Y by introducing an intermediate variable M through which the effect travels, producing an indirect pathway X → M → Y. Moderation, by contrast, describes a situation where the strength or presence of the X → Y relationship changes depending on the level or group of another variable (the moderator), so the effect is conditional. The best statement captures this by saying mediation involves X predicting Y through M, illustrating the indirect route, while moderation involves X predicting Y only for a particular group or level of the moderator, reflecting a conditional effect. For example, stress (X) might affect burnout (Y) via workload (M) in a mediation scenario. In moderation, the impact of stress on burnout might be stronger when social support (moderator) is low and weaker when support is high, showing the effect depends on the moderator’s level. The other options mix up these ideas: moderation is not defined by an indirect path, and mediation is not defined by group differences alone, and they are not the same concept.

The key idea is to distinguish mechanism from conditional effect. Mediation explains how or why X influences Y by introducing an intermediate variable M through which the effect travels, producing an indirect pathway X → M → Y. Moderation, by contrast, describes a situation where the strength or presence of the X → Y relationship changes depending on the level or group of another variable (the moderator), so the effect is conditional.

The best statement captures this by saying mediation involves X predicting Y through M, illustrating the indirect route, while moderation involves X predicting Y only for a particular group or level of the moderator, reflecting a conditional effect. For example, stress (X) might affect burnout (Y) via workload (M) in a mediation scenario. In moderation, the impact of stress on burnout might be stronger when social support (moderator) is low and weaker when support is high, showing the effect depends on the moderator’s level.

The other options mix up these ideas: moderation is not defined by an indirect path, and mediation is not defined by group differences alone, and they are not the same concept.