be a mediator of connection X → Y, if (c – c′) is significantly different from 0, which is mathematically equivalent to the product of the paths a× b (MacKinnon et al., 2007). If the product of a× b and the paths a and b are significant, one concludes that X → Y is mediated by M. In addition, if path c′ is not significant, it indicates that there is no direct connection from X to Y and that X → Y is completely mediated by M. Note that path b is the relation between Y and M, controlling for X, and it should not be confused with the correlation coefficient between Y and M. Note that a significant correlation between X and Y and between X and M is required for one to perform the mediation test.
