I did a simple mediation analysis using PROCESS (attached). The result is all significant however the path "b" or M -> Y is negative. I've read somewhere, Zhao et al., that this is called "competitive mediation?", BUT i do not know how to explain or interpret the result. Can anybody explain this?
Thank you.
The positive sign for the a path means that $X$ is positively associated with $M$, and the negative sign for the b path merely means that $M$ is negatively associated with $Y$ (as $M$ increases, $Y$ tends to decrease). In other words, increases in $X$ predict increases in $M$, which, in turn, predict decreases in $Y$. The significant mediation indicates that part of the statistical association between $X$ and $Y$ is transmitted indirectly through changes in $M$, regardless of the specific sign for the a and b paths.
I'm not familiar with the term "competitive mediation". However, it seems to refer to the fact that the direct effect of $X$ on $Y$ is positive, whereas the mediation model suggests that increases in $X$ are indirectly associated with decreases in $Y$, through increases in $M$.
Competitive mediation happens when both the direct and indirect effects are significant and pointing to opposite direction while complementary mediation refers to a condition when both the indirect and direct effects are significant and pointing to the same direction.
As stated by Ahmed competitive mediation is when the direction of the relationship of the mediated effect is different to (competes with)the direction of the relationship direct effect. A further distinction can be drawn between full and partial mediation where the mediated effect explains all of the variance or part of it. If it is a full mediation then the effect of X on the Y should disappear (because it is now being accounted for entirely by the mediated effect).
In full competitive mediation, X and Y could have a positive relationship while X and M would have a negative relationship, and also M and Y would have a negative relationship (complementary). In partial competitive mediation, the relationships between X and M and between M and Y would differ (compete).
Competitive mediation is familiar for me because we studied the Baron and Kenny (1987) paper. We learned the concept in master level research methods in M.S organizational and industrial psychology in Iran / Isfahan. Competitive mediation is a type of partial mediation that occurs when is removed the mediating variable relationship between X and Y is existed too and significant.
Competitive mediation and complementary mediation are two types of partial mediation. When we cross these signs of a, b, and c together, if result is negative, we deduce this is competitive mediation. But if, when we cross these signs 0f a, b, and c toghether, the result is positive, we deduce this is a complementary mediation.
