A mediational hypothesis is that kind of hypothesis in which it is assumed that the affect of an independent variable on a dependent variable is mediated by the process of a mediating variable and the independent variable may still affect the independent variable. In other words, in mediational hypothesis, the mediator variable is the intervening or the process variable. The mediational hypothesis assumes the complete mediation in the variables.
The term complete mediation in mediational hypothesis means that the independent variable does not at all affect the dependent variable after the mediator variable has controlled it. The mediation model involved in mediational hypothesis is a causal model.
Baron & Kenny’s procedures describes the analyses which are required for testing various mediational hypothesis.
The first step involved in Baron & Kenny’s procedures is that the researcher must be shown that the initial variable is being correlated with the outcome variable. In other words, the first step in Baron & Kenny’s procedures involves the establishment of an effect which may be mediated.
The second step involved in Baron & Kenny’s procedures is that the researcher must be shown that the initial variable is being correlated with the mediator. In other words, the second step in Baron & Kenny’s procedures involves treating the mediator variable as an outcome variable.
The third step in Baron & Kenny’s procedures involves an establishment of the correlation between the mediator variable and the outcome variable. In this step of Baron & Kenny’s procedures, there exists correlation between the mediator and the outcome variable because they both are caused due to the initial variable. In other words, in Baron & Kenny’s procedures, the initial variable must be controlled while establishing the correlation between the two other variables.
The next step in Baron & Kenny’s procedures involves the establishment of the complete mediation across the variables. This establishment in the last step of Baron & Kenny’s procedures can only be achieved if the affect of the initial variable over the outcome variable while controlling for mediator variable is zero.
If all four steps of Baron & Kenny’s procedures are met, then the data is consistent with the mediational hypothesis. If, however, only the first three steps of Baron & Kenny’s procedures are satisfied, then partial mediation is observed in the data.
The researcher should keep in mind that if the steps involved in Baron & Kenny’s procedures are completely satisfied, it still does not imply that the mediation has occurred as there are other less plausible models that are consistent with the data.
The mediator variable in mediation hypothesis can be caused by the outcome variable. This happens when the initial variable is a manipulated variable—then it cannot be caused either by the mediator or the outcome in mediation hypothesis. However, since both the mediator and the outcome variables are not manipulated, they may cause each other in mediational hypothesis.
It is always sensible to swap the mediator variable and the outcome variable and have the outcome cause the mediator in mediational hypothesis.
