Endogenous Moderator Models: What They are, What They Aren’t, and Why it Matters

Models that combine moderation and mediation are increasingly common. One such model is that in which one variable causes another variable that, in turn, moderates the relationship between two other variables. There are many recent examples of these Endogenous Moderator Models (EMMs). They bear little superficial resemblance to second-stage moderation models, and they are almost never conceptualized and tested as such. We use path analytic equations to show that this is precisely what EMMs are. Specifically, we use these path analytic equations and a review of recent EMMs in order to show that these models are seldom conceptualized or tested properly and to understand the best ways to handle such models. We then use Monte Carlo simulation to show the consequences of testing these models as they are typically tested rather than as second-stage moderation models. We end with recommendations and provide example datasets and code for SPSS and R.