During the pandemic many political leaders have been heard to justify their decisions by telling us that they were following advice from scientists. I think it was Thomas Kuhn who proposed that the views of a group of scientists will be normally distributed if the group is large enough, i.e., a bell-shaped curve with a few scientists providing outlying opinions on either end and the majority in the middle of the distribution [see ‘Uncertainty about Bayesian methods’ on June 7th, 2017]. So, it depends which scientist you consult as to what advice you will receive. Of course, you can consult a group of experts in order to identify the full range of advice and seek a consensus; however, this is notoriously difficult because some voices will be louder than others and some experts will be very certain about their predictions of the future while others will be very cautious about predicting anything. This is often because the former group are suffering from meta-ignorance, i.e., failing to even consider the possibility of being wrong, while the latter are so aware of the ontological or deep uncertainties that they prefer to surround their statements with caveats that render them difficult or impossible to interpret or employ in decision-making [see ‘Deep uncertainty and meta ignorance’ on July 21st 2021]. Politicians prefer a simple message that they can explain to the media and tend to listen to the clear but usually inaccurate message from the confident forecasters [see ‘Forecasts and chimpanzees throwing darts’ on September 2nd, 2020]. However, with time and effort, it is possible to make rational decisions based on expert opinion even when the opinions appear to diverge. There are several recognised protocols for expert elicitation which are used in a wide range of engineering and scientific activities to support decision-making in the absence of comprehensive information. I frequently use a form of the Sheffield protocol developed originally to elicit a probability distribution for an unknown uncertainty from a group of experts. Initially, the group of experts are asked individually to provide private, written, independent advice on the issue of concern. Subsequently, their advice is shared with the group and a discussion to reach a consensus is led by a facilitator. This can be difficult if the initial advice is divergent and individuals hold strong views. This is when RIO can help. RIO stands for Rational Impartial Observer and an expert group often rapidly reach a consensus when they are asked to consider what RIO might reasonably believe after reading their independent advice and listening to their discussion.
Anthony O’Hagan, Expert knowledge elicitation: subjective but scientific, The American Statistician, 73:Sup.1, 69-81, 2019.
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