Desirability bias in foresight: Consequences for decision quality based on Delphi results

In foresight activities uncertainty is high and decision makers frequently have to rely on human judgment. Human judgment, however, is subject to numerous cognitive biases. In this paper, we study the effects of the desirability bias in foresight. We analyze data from six Delphi studies and observe that participants systematically estimate the probability of occurrence for desirable (undesirable) future projections higher (lower) than the probability for projections with neutral desirability. We also demonstrate that in the course of a multi-round Delphi process, this bias decreases but is not necessarily eliminated. Arguably, the quality of decisions based on Delphi results may be adversely affected if experts share a pronounced and common desirability for a future projection. Researchers and decision makers have to be aware of the existence and potential consequences of such a desirability bias in Delphi studies when interpreting their results and taking decisions. We propose a post-hoc procedure to identify and quantify the extent to which the desirability bias affects Delphi results. The results of this post-hoc procedure complement traditional Delphi results; they provide researchers and decision makers with information on when and to which extent results of Delphi-based foresight may be biased.

Research highlights
► Experts’ probability estimates for far future projections can be affected by the desirability bias.
► The desirability bias decreases but is not necessarily eliminated in the course of a multiround Delphi process.
► The quality of decisions based on Delphi results may be adversely affected by the desirability bias.
► Traditional Delphi results can be complemented by information on the extent to which Delphi-based forecasts may be biased.