Method note [1]: Mediation and Moderation Effects

The inclusion of third variables (mediating and moderating) hoffers the promise of significantly adding the amount of informaiton with practical interpretations and testing the theory. Givent the potentials to make the study outcomes far more interesting and significant, including the mediating and moderating variables is probably the most cost-effective investment.
Primary questions in exmpirical design intervention research are " How and what extent the intervention work?" and "for whom (group) does the intervention work?"

How & What extent the intervention work? - Mediation Effects

interventions are mediating variables that describe the process by the intervention chieves the effects