Have you ever wondered if birth order effects vary across ethnic groups? Whether a particular clinical intervention is likely to yield dissimilar outcomes for men and women? Or if the effectiveness of a sales promotion is dependent on a market segment? Questions like these can be effectively answered by using a statistical tool known as moderated multiple regression (MMR). This book provides practical guidance for using MMR to better assess whether the relationship between two quantitative variables is moderated by group membership. Included are discussions and fully worked-out examples of how to conduct and interpret MMR analysis, as well as descriptions of computer programs that allow investigators to check whether their MMR test for moderation can be trusted. Using examples from a variety of different disciplines--from psychology and education to management and political science--Herman Aguinis first shows readers how to distinguish between moderated and mediated relationships. Next, he presents a description of the MMR procedure and its basic statistical assumptions, explains how to conduct an MMR analysis using computer packages, and demonstrates how to interpret the resulting output.