“Heuristic Device: Any procedure which involves the use of an artificial construct to assist in the exploration of social phenomena. It usually involves assumptions derived from extant empirical research. For example, ideal types have been used as a way of setting out the defining characteristics of a social phenomenon, so that its salient features might be states as clearly and explicitly as possible. A heuristic device is, then, a form of preliminary analysis. Such devices have proved especially useful in studies of social change, by defining bench-marks, around which variation and differences can then be situated. In this context, a heuristic device is usually employed for analytical clarity, although it can also have explanatory value as a model.”
Excerpted from: Marshall, Gordon, ed. Oxford Dictionary of Sociology. New York: Oxford University Press, 1994.