What is a mediator?

• A. The reason why there appears to be a relationship between the independent and dependent variables; it must be a causal result of the IV and a causal antecedent of the DV.
• B. A variable that changes the direction of the relationship depending on groups.
• C. The dependent variable.
• D. An extraneous variable.

Answer: (A)

Mediation explains how or why an effect occurs by identifying the intermediary process that transmits the influence of one variable to another. A mediator is a variable that is causally influenced by the independent variable and, in turn, causally influences the dependent variable, placing it on the pathway from IV to DV (IV → mediator → DV). This is why it accounts for the relationship between the IV and DV: it reveals the mechanism through which the IV affects the DV.

In contrast, the dependent variable is simply the outcome you measure, while an extraneous variable is an uncontrolled factor that could confound the relationship. A moderator is a variable that changes the strength or direction of the IV–DV relationship across different groups.