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Do ‘big losses’ in judgmental adjustments to statistical forecasts affect experts’ behaviour?

Research output: Contribution to Journal/MagazineJournal articlepeer-review

<mark>Journal publication date</mark>16/03/2016
<mark>Journal</mark>European Journal of Operational Research
Issue number3
Number of pages11
Pages (from-to)842-852
Publication StatusPublished
Early online date6/06/15
<mark>Original language</mark>English


The behaviour of poker players and sports gamblers has been shown to change after winning or losing a significant amount of money on a single hand. In this paper, we explore whether there are changes in experts’ behaviour when performing judgmental adjustments to statistical forecasts and, in particular, examine the impact of ‘big losses’. We define a big loss as a judgmental adjustment that significantly decreases the forecasting accuracy compared to the baseline statistical forecast. In essence, big losses are directly linked with wrong direction or highly overshooting judgmental overrides. Using relevant behavioural theories, we empirically examine the effect of such big losses on subsequent judgmental adjustments exploiting a large multinational data set containing statistical forecasts of demand for pharmaceutical products, expert adjustments and actual sales. We then discuss the implications of our findings for the effective design of forecasting support systems, focusing on the aspects of guidance and restrictiveness.