What is Mediation?
Mediation in behavioral science refers to the process by which an independent variable influences a dependent variable through an intermediate variable (the mediator). It answers the question: how or why does the effect occur?
How it works
If exercise reduces depression, mediation analysis asks: through what mechanism? Possible mediators include increased serotonin (biological), improved self-efficacy (psychological), or expanded social contact (social). Identifying the mediator has practical implications: if social contact is the primary mediator, then group exercise should be more effective than solo exercise. Baron and Kenny’s (1986) four-step approach is the classic method, though modern approaches use structural equation modeling and bootstrapping for more robust inference.
Applied example
Research showing that a mindfulness intervention reduces stress might find through mediation analysis that the effect operates through improved attention regulation (the mediator) rather than relaxation. This means that other interventions targeting attention regulation could produce similar stress benefits.
Why it matters
Mediation reveals the mechanism inside the black box of ‘it works,’ enabling more efficient intervention design by targeting the active ingredient directly.
