with Andrew Hayes, PhD
As research in any particular area develops and evolves, attention naturally shifts away from establishing the existence of some kind of causal effect between two variables to understanding how the effect operates (mediation) and when the effect exists or is strong versus when it is absent or weak (moderation). Few would dispute that all effects exist through some kind of mechanism, and all effects have boundary conditions. Thus, an analysis which attempts to answer only how or when but not both are necessarily incomplete in significant ways. Recently, methodologists have been describing approaches to integrating moderation and mediation analysis into a single integrated model.