Hi all. I am attempting to test a mediation hypothesis. There is a significant correlation between my mediator variable and my DV. However, when I further examined the nature of this relationship by regressing the DV onto the mediator and including a quadratic term, my output indicates that both the linear model and the quadratic model are significant, and that actually my quadratic model accounts for slightly more variance than the linear model (however, both Rs are small). What is the importance of this finding? Does this mean it is inappropriate to test a mediation hypothesis given the existence of a non-linear relationship between the mediator and DV? Or can I go ahead with the mediation and just note that as a limitation??