Interaction Terms

To Moderate or to Mediate?

May 21st, 2018 by

We get many questions from clients who use the terms mediator and moderator interchangeably.

They are easy to confuse, yet mediation and moderation are two distinct terms that require distinct statistical approaches.

The key difference between the concepts can be compared to a case where a moderator lets you know when an association will occur while a mediator will inform you how or why it occurs.


Testing and Dropping Interaction Terms in Regression and ANOVA models

February 26th, 2009 by

In a Regression model, should you drop interaction terms if they’re not significant?

In an ANOVA, adding interaction terms still leaves the main effects as main effects.  That is, as long as the data are balanced, the main effects and the interactions are independent.  The main effect is still telling (more…)