Dealing with Expert Bias in Collective Decision-Making

Quite some real-world problems can be formulated as decision-making problems wherein one must repeatedly make an appropriate choice from a set of alternatives. Multiple expert judgements, whether human or artificial, can help in taking correct decisions, especially when exploration of alternative solutions is costly. As expert opinions might deviate, the problem of finding the right alternative can be approached as a collective decision making problem (CDM) via aggregation of independent judgements. Current state-of-the-art approaches focus on efficiently finding the optimal expert, and thus perform poorly if all experts are not qualified or if they are overly biased, thereby potentially derailing the decision-making process. In this paper, we propose a new algorithmic approach based on contextual multi-armed bandit problems (CMAB) to identify and counteract such biased expertise. We explore homogeneous, heterogeneous and polarised expert groups and show that this approach is able to effectively exploit the collective expertise, outperforming state-of-the-art methods, especially when the quality of the provided expertise degrades. Our novel CMAB-inspired approach achieves a higher final performance and does so while converging more rapidly than previous adaptive algorithms. ∗Corresponding author Email addresses: axel.abels@ulb.be (Axel Abels), tom.lenaerts@ulb.be (Tom Lenaerts), vito.trianni@istc.cnr.it (Vito Trianni), ann.nowe@vub.be (Ann Nowé) ar X iv :2 10 6. 13 53 9v 2 [ cs .A I] 2 9 A ug 2 02 2