The (redundant) effect that an input might have upon an endogenous quantity reachable by it is characterized. The implication for an output is inferred by directional duality. Unsigned measures of redundancy are formulated and discussed. Then signed measures are developed by definition of the terms “excitatory redundancy,” “inhibitory redundancy,” and “contradictory redundancy.” The concept of an “EI space” is presented as a visual means of displaying the structural effect of an input upon an endogenous quantity. The EI space also enables assessment of the degree of proximity between a pair of inputs in terms of the effect each has upon the same endogenous quantity and permits the aggregated effect of all inputs upon the quantity to be determined. These methods provide managerial insight into the behavioral nature of the causality inherent within a structural model.