CONFIDENCE AND UNCERTAINTY IN JUDGMENTAL FORECASTING - DIFFERENTIAL-EFFECTS OF SCENARIO PRESENTATION

hMultiple scenario analysis is used by many organizations for long-ter m planning, in part because the development of more than one scenario of the future is thought to prevent overconfidence in any one specific forecast. The present study attempts to clarify some of the questions concerning the cognitive effects of scenario presentation by distingu ishing between confidence and subjective uncertainty. It examined the impact of different types of scenario information on confidence rating s, credible intervals, and features of forecast series. Subjects (N=18 6) read either one, two, or no scenario(s) describing potential change s in the level of a stimulus variable, then made forecasts of that var iable over the next fifty years. Reading any type of scenario informat ion increased confidence in forecasts; there was no reduction in confi dence due to presentation of multiple conflicting scenarios, compared to presentation of only one scenario. Differences in number and in typ e of scenarios presented did, however, affect subjective uncertainty.