By the end of this chapter, you will be able to do the following:

9.1 Formulate why you should care about regression analysis.

9.2 Assess moderation effects in your research.

9.3 Manage the eight problems related to moderation: (1) lack of attention to measurement error, (2) variable distributions are assumed to include the full range of possible values, (3) unequal sample size across moderator-based categories, (4) insufficient statistical power, (5) artificial dichotomization of continuous moderators, (6) presumed effects of correlations between product term and its components, (7) interpreting first-order effects based on models excluding product terms, and (8) graphs that exaggerate the size of interaction effects.

9.4 Assess mediation effects in your research.

9.5 Manage the six problems related to mediation: (1) requiring a significant relation between the antecedent and the outcome, (2) disregarding the magnitude of the indirect effect, (3) testing the direct effect as a condition for mediation, (4) including a direct effect without conceptual justification, (5) testing mediation with cross-sectional data, and (6) lack of attention to measurement error.

9.6 Set up and perform Analysis of Covariance (ANCOVA) in your research.

9.7 Design studies that address nonlinear effects, including the too-much-of-a-good-thing (TMGT) effect: A formalized meta-theory used in several research domains.

9.8 Appraise the implications of the TMGT effect for your future research, including implications for theory development and theory testing (including statistical power and effect size, range restriction, advanced meta-analytic methods, and advanced growth modeling methods).