Intervening variable

An intervening variable is a hypothetical concept that attempts to explain relationships between variables, and especially the relationships between independent variables and dependent variables. It is often distinguished from a hypothetical construct in that it has no properties other than those observed in empirical research. That is, it is simply a summary of the relationships observed between independent 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).

On the other hand, one can make the statement that acquaintance with members of other races and exposure to anti-racist education reduces intolerant behaviour towards members of other races and increases social interaction with members of other races. This statement is phrased so generally that it must imply relationships which have not been observed. A hypothetical construct of tolerance could be posited as a means of explaining the relationships between these and other variables.