Mean Centering in Moderated Multiple Regression: Much Ado about Nothing

Abstract

Centering variables prior to the analysis of moderated multiple regression equations has been advocated for reasons both statistical (reduction of multicollinearity) and substantive (improved interpretation of the resulting regression equations). This article provides a comparison of centered and raw score analyses in least squares regression. The two methods are demonstrated to be equivalent, yielding identical hypothesis tests associated with the moderation effect and regression equations that are functionally equivalent.