Abstract

Tversky and Kahneman (1974) originally discussed three main heuristics: availability, representativeness, and anchoring-and-adjustment. Research on judgemental forecasting suggests that the type of information on which forecasts are based is the primary factor determining the type of heuristic that people use to make their predictions. Specifically, availability is used when forecasts are based on information held in memory; representativeness is important when the value of one variable is forecast from explicit information about the value of another variable; and anchoring-and-adjustment is employed when the value of a variable is forecast from explicit information about previous values of that same variable. Although there has been increased emphasis on the adaptiveness of heuristics and increased interest in specifying their use in terms of computational models, this way of structuring our knowledge about judgemental forecasting continues to be a useful one. I use it to frame discussion of some recent debates in the area.