intervening variable A variable, used in the process of explaining an observed relationship between an independent and dependent variable(s), such that X → T → Y—where T is the intervening variable which is used to explain the X → Y relationship. For example, if X is age and Y is reading ability, the causal relationship between X and Y might be explained by the intervening variable T, say education, which explains the X → Y link. Hence X is an indirect cause of Y through the intervening variable T: T predicts Y but is simultaneously predicted by X.

variable, intervening See INTERVENING VARIABLE.