A general purpose computer aid to judgemental forecasting: Rationale and procedures

摘要

Here we describe the rationale, procedures and use of a general purpose computer aid to judgemental forecasting. First, we review empirical studies of unaided judgemental forecasting and we identify suboptimalities in such probabilistic judgements. Next we present a description of ‘Forecast’, illustrating how the program's procedures aid judgemental forecasting by enabling the forecaster to produce coherent and consistent probabilities. The program aids three types of forecasting: first, of the time period or date when a specified event may happen, e.g. the value of UK £1.00 falling below US$1.30; second, the possible outcomes of an event when these can be expressed in numerical terms as outcomes on a single continuous scale, e.g. company profits; third, the possible outcomes of an event when these can be expressed as discrete or discontinuous outcomes, e.g. the winner of a horse race.