In a mediation model, which term represents the portion of the predictor's effect on the outcome that is not transmitted through the mediator?

• A. Indirect effect
• B. Mediator effect
• C. Total effect
• D. Direct effect

Answer: (D)

The main idea is breaking the X → Y effect into parts: what goes through the mediator and what does not. The direct effect is the portion of X’s impact on Y that remains when you account for the mediator, i.e., the part not transmitted via M. The indirect effect, in contrast, is the portion that travels from X to M to Y (the product of the X→M and M→Y paths). The total effect of X on Y is the sum of these two components. So, the term that represents the portion not transmitted through the mediator is the direct effect. If that direct portion is zero, you have complete mediation; if it’s nonzero, you have partial mediation.