How do we articulate the relative salience, strengths and impacts of mediators and moderators in a model ? Typically the narrative is that a moderator acts to infuence the relationship between an IV and the DV. Its absence in a model does not disturb the realtionship between IV and DV. On the other hand, in the case of a mediator, the direct relationship between the IV and DV weakens or disappears in the presence of the mediator; the IV to M and M to DV being the strongest path. Where the a priori specific role (mod or med) in a model is clearly theory-driven, then there is no ambiguity. There are many cases, however, where the role is ambigious. Similarly, in scenarios of theory building (as opposed to theory testing) no apriori preecedent would exist to guide. In those cases how is the intermediary variable determined ? Can a mediator moderate ? Can a moderator mediate ?
In general, either moderator or mediator can not swap the role. Yet, to provide accurate answer, could you give a specific variables (and its construct) that you are referring to ?
Silburn,
Try this link: https://kuscholarworks.ku.edu/bitstream/handle/1808/1658/preacher_rucker_hayes_2007.pdf?sequence=1&isAllowed=y
And this: http://webcom.upmf-grenoble.fr/LIP/DMuller/resources/documents/MJY_2005_jpsp.pdf
Hope it helps
Marina
Marina,
Thanks for sharing these two articles.
In relation to the cases of moderated mediation and mediated moderation, Muller,Yzerbyt & Judd's conclusion was particularly insightful.
"..it became apparent to us, as our ideas (and this article) evolved, that we had much more to say at a theoretical level about the inherent similarities between the two processes (mediated moderation and moderated mediation). They both rely on the same analytic models, they both imply moderated indirect effects of the treatment variable on the outcome, and they both imply that the overall moderation of the treatment effect is altered once the (moderated) mediating process is controlled. At the same time, we would not want to claim that moderated mediation and mediated moderation are one and the same. By defining the prototypic moderated mediation case, we can clearly differentiate between them. Additionally, mediated moderation clearly does imply that the overall moderation of a treatment effect is reduced once the (moderated) mediating process is controlled.
That said, however, we also have argued that if one allows for the possibility of moderated mediation in cases where there is overall moderation of the treatment effect, then the distinction between the two processes can become more a matter of theoretical preference than anything else. Is the emphasis on the reduction of the moderation of the treatment effect once the (moderated) mediating process is controlled? Or is the emphasis more on the fact that there is a moderated mediating process? The analytic models are clear cut and the two processes can be defined in the prototypic cases.
But these, as we have already said, represent probably two sides of the same coin. In talking about that coin, we can either concentrate on describing each side in turn, or we can recognize that they both define the common coin."
Thanks Krishtian,
Trying to stretch the thinking on the ideas of mediation and moderation.
Let's use case of the 3D HiLo surface graphs as an example. Would it be appropriate to use these graphs for portraying the effects of both types of intermediary variables on a relation; ie both mediators and moderators
Marina Ramkissoon Silburn Clarke @ Do have a reference or article, where the same variable has been used as mediator and moderator in one study. Khristian Edi Nugroho Soebandrija please have look on the attached ppt. Whats your opinion after going through the slides.
Is it possible to use the same variable as mediator and moderator in the same model/study...
can a variable be both a mediator and a moderator?
Asadullah,
The Conditional Process Analysis (CPA) approach of Prof Andrew F Hayes, has proven superior to the traditional Baron & Kenny model (see below) which has some weaknesses. More on CPA below.
Silburn
Book Introduction to Mediation, Moderation, and Conditional Proce...
Hayes, A. F. (2012). PROCESS: A versatile computational tool for observed variable mediation, moderation, and conditional process modeling [White paper]. Retrieved from http://www.afhayes.com/ public/process2012.pdf
Hayes 2009 Beyond Baron and Kenny: Statistical Mediation Analysis in the New Millennium
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