The Statistical, Theoretical, and Practical Significance of an Empirical Effect

A comprehensive evaluation of an empirical effect should address the size of the effect (statistical aspect), the ability to explain and predict this effect using a theoretical construct (theoretical aspect), and the utility ascribed to it (practical aspect). In the case of the empirical aspect, researchers do not so much evaluate but statistically describe an effect as a parameter estimate. In the case of the theoretical aspect, the evaluation addresses whether this parameter estimate explains the observations that inductively ground the effect size estimate, respectively whether a theoretical construct predicts new observations of this effect. Contrary to what the synonymous use of ‘explain’ and ‘predict’ suggests, the standards for an adequate explanation differ from those for an adequate prediction. This, we argue, has important implications for the smallest effect of interest that offers a worthwhile parameter for theory construction research. In the case of the practical aspect, finally, the evaluation concerns the amount of utility that is ascribed to a stable population effect.