Abstract
Trade-offs between quality and quantity arise in an abundance of contexts concerning group decision making. With the starting point being that group members provide more accurate evidence when they are involved with fewer tasks, team managers often encounter the following dilemma: Should they assign their group members with many tasks (attempting to gather more evidence with lower quality), or with fewer tasks (aiming at receiving less, but more high-quality evidence)? Secondly, what is the optimal way to aggregate the collected evidence from a group, which may be contrasting and varying in accuracy? Should more weight be given to the more accurate group members, or to the larger number of those who provide the same answer? After summarising the observations stemming from a mathematical model designed to address these issues, we complement it experimentally by investigating to what extent people’s decision-making patterns are in accordance with the optimal ones proposed by the normative framework. We find that people make close to optimal decisions as they manage evidence, but tend to prefer the majority rule—contrary to the optimal rule—when they aggregate them.