Maineffects
Maineffects, in statistics and experimental design, refer to the effect of a single factor on the outcome variable, averaged across the levels of other factors in a factorial design. In a study with two factors, A and B, the main effect of A is the difference in the dependent variable between the levels of A, averaged over B. This is equivalent to comparing marginal means: the mean response at each level of A after averaging over B.
Main effects are typically estimated using analysis of variance (ANOVA) or multiple regression with appropriate coding
Interpreting main effects becomes more complex in the presence of interactions. A significant interaction indicates that
Maineffects are a foundational concept in factorial experiments and ANOVA, providing a concise summary of how