The law of maximum expected potential effect: constraints placed on program effectiveness by mediator relationships

The application of mediating variable analysis can yield information about the potential effectiveness of interventions that target social behavior. The application of widely accepted statistical equations to the analysis of simulated data demonstrates that the magnitude of the relationship between mediators and behavioral outcomes directly affects the maximum expected potential effect size that can be achieved for any given intervention. The use of this relationship in planning and executing interventions is described. Elements that the field needs to develop before a truly prospective system of forecasting program effectiveness are outlined.