Intervening variable

An intervening variable is a hypothetical construct that attempts to explain relationships between variables, and especially the relationships between independent variables and dependent variables.

For example, hunger is a hypothetical internal state which has been used to explain the relationships between independent variables such as length of time without food or amount of food consumed and dependent variables which are measures of eating. Intervening variables may be useful in reducing the number of relationships which need to be explained; for example, in attempting to explain the relationships between five independent variables and two dependent measures of eating, the use of the intervening variable of hunger reduces the number of relationships to be explained from ten to seven (five between the independent variables and hunger, and two between hunger and the dependent variables).

Similarly, one can make the statement that by attending school, one increases tolerance for other races. "Attending school" would be the independent variable, and "tolerance" the dependent. However, the act of attending school itself does not create racial tolerance, rather it comes as a result of a being exposed to students of other races and being exposed to tolerance education within the classroom. Therefore, we can state that the intervening variable in this scenario is "education."