| Abstract: | Nearly 500 annual sales forecasts were generated from the responses of 82 subjects who were presented with either a time-series plot of historical sales data by itself or with the same plus three scenarios, and were then asked to make forecasts. Sales forecasts were made in either a stable or an unstable environment. The findings did not support the claims made by scenario advocates. Scenarios did not make unexpected outcomes less surprising. Instead, scenarios were found to increase confidence in a favored forecast. Furthermore, no support was found for the contention that scenarios improved upon ‘eyeball’ extrapolations or made judgmental sales forecasts more accurate than quantitative extrapolations. Scenarios were found to be tainted by many of the same biases previously identified by cognitive psychologists. |
