Visual heuristics for marginal effects plots

Abstract

Common visual heuristics used to interpret marginal effects plots are susceptible to Type-1 error. This susceptibility varies as a function of (a) sample size, (b) stochastic error in the true data generating process, and (c) the relative size of the main effects of the causal variable versus the moderator. I discuss simple alternatives to these standard visual heuristics that may improve inference and do not depend on regression parameters.