Prevention Science

, Volume 10, Issue 2, pp 87-99

First online:

A General Model for Testing Mediation and Moderation Effects

  • Amanda J. FairchildAffiliated withDepartment of Psychology, University of South Carolina, Barnwell College Email author 
  • , David P. MacKinnonAffiliated withResearch in Prevention Lab, Department of Psychology, Arizona State University

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This paper describes methods for testing mediation and moderation effects in a dataset, both together and separately. Investigations of this kind are especially valuable in prevention research to obtain information on the process by which a program achieves its effects and whether the program is effective for subgroups of individuals. A general model that simultaneously estimates mediation and moderation effects is presented, and the utility of combining the effects into a single model is described. Possible effects of interest in the model are explained, as are statistical methods to assess these effects. The methods are further illustrated in a hypothetical prevention program example.


Mediation Indirect effect Moderation Mediated moderation Moderated mediation