¶ … Mediation Theory

Let the discussion of mediation and moderation begin briefly with what they have in common and proceed further into what distinguishes them. Mediation and moderation are types of hypotheses most found within experimental design models. Mediation and moderation are hypotheses that describe the ways in which causes relate to their respective effects. Mediation and moderation may additionally be described as theories used to further distinguish and articulate processes within a causal relationship. The particular methodology of mediation and moderation are found in some of the following disciplines: sociology, psychology, and social science. Researchers who endeavor to use this methodology would benefit from taking content from a network or spectrum of disciplines to maximize readership.

This definition does not restrict experiments only to designs with randomization, and mediation and moderation is not restricted only to those causal relationships that are established based on randomized experiments. Nonetheless, the power of an experiment in making causal claims does depend on how much control a researcher has in the design (i.e., the operations of the independent variable, Holland 1986). The more control one has over the experiment, the more power one has in making strict causal inferences. This notion is widely known as the internal validity of an experiment (Cook and Campbell 1979; Shadish et al. 2002). (Wu & Zumbo, Understanding & Using Mediators and Moderators, 2008)

Mediation and moderation are theories and hypotheses used by social and health scientists as ways to understand and explain how a cause produces an effect. The use of mediation and moderation as a research method requires a specific procedure including a distinctive theoretical...

Mediation and moderation are causal models.
In research, there are causes and effects or independent variables and dependent variables. Mediators and moderators are also a third type of variable in the causal relationship. (Wu, Zumbo, 2008) A mediator is a variable that links a cause to an effect while a moderator is a variable that modifies the effect with a distinctive cause. Mediators, mediation, or the mediative causal model further defines the reason for the cause and effect and the method by which the cause and effect happen or occur. Mediation is considered more affective in nature:

A mediator is often a cognitive, affective, physiological, motivational state that functions as a person's psychological process after receiving a stimulus such as intervention treatments (Hoyle and Robinson 2003). In turn, the responsive changes in the mediator leads to the change in the outcome…Theoretically and conceptually, a mediator should be a responsive variable that changes within a person. For this reason, psychological constructs that are believed to be relatively more stable such as personality traits (e.g., extraversion) or innate attributes (e.g., gender or ethnicity) are less likely to be a candidate for a mediator. (Wu & Zumbo, Understanding & Using Mediators and Moderators, 2008)

Mediation is supposed to explain a process and connection between the cause and the effect. Mediation, just as when the term is used in reference to a form of counseling, is a causal model, hypothesis or theory that is the go between the cause and the effect or the independent variable and the dependent variable. Mediation is the filling in the cause and effect sandwich. Moderation distinguishes the period during which the cause and effect occurs and…