Elaborating or Aggregating? The Joint Effects of Group Decision-Making Structure and Systematic Errors on the Value of Group Interactions

Abstract

We explore when group interactions will have a positive effect on the accuracy of quantitative judgments. The results from two laboratory experiments revealed that the value of group interactions, compared to a statistical aggregation of individual judgments, depends strongly on how a group is structured, and that this effect is moderated by the level of systematic error among group members. In particular, when there was a low level of systematic error, group interactions generally provided little value and group structure did not have a significant effect on the value of group interactions. However, when the level of systematic error was high, the value of interactions in groups with a designated group leader was strongly positive and significantly higher than in consensus groups where interactions still provided only little value. Moreover, our analysis showed that this effect was mediated by information elaboration—which was generally higher in leader groups but only had a significant effect on the value of group interactions when there was a high level of systematic error among group members, and not otherwise. Consistent with these findings, we also found that when the level of systematic error was high, leader groups made more judgments that were outside of the range of initial individual judgments than consensus groups. Furthermore, members of leader groups in general spent more time discussing their task, and reported a higher motivation to process information systematically.