What is Moderation analysis?
Moderation analysis is the statistical procedure for testing whether the effect of one variable on another varies across levels of a third variable. It typically tests an interaction effect in regression or ANOVA.
How it works
The analysis includes the independent variable, the moderator, and their interaction term. A significant interaction indicates moderation: the effect of X on Y differs depending on the level of M. The interaction can be probed using simple slopes analysis, which tests the effect of X on Y at specific levels of M (e.g., low, medium, high). Johnson-Neyman analysis identifies the exact range of the moderator for which the effect is significant.
Applied example
A company tests whether a new training program improves sales performance. Moderation analysis reveals a significant interaction with experience level: the program boosts sales for new hires but not for experienced salespeople. This finding saves the company from mandating training that is unnecessary for experienced staff.
Why it matters
Moderation analysis enables precision in intervention delivery by identifying which subgroups benefit most, transforming blanket interventions into targeted ones.
