An Analysis of Ghiselli's Moderator Variable

Abstract

A mathematical model for Ghiselli's moderator variable and index of predictability is developed. From this mathematical structure, conclusions and implications are drawn concerning the use of moderators in multiple regression and suppression. In addition, guides are given as to when and where to look for moderators. Finally, the structure is related to Wiggins' “components of variance” in order to show how moderator and index of predictability situations might arise.