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The most effective method for aggregating the conflicting opinions of experts is a subject of active debate in the literature. Task differences are most often used to explain differing results among studies. Alternatively, we suggested that the characteristics of the interacting groups themselves determine whether they outperform or underperform their equivalent composites. Expert loan officers serving in ad hoc and practiced groups, on average, performed equally as well as did their composite and most influential individual. However, whether a particular group outperformed or underperformed its composite could be explained by variation in group members' performances and abilities to recognize differential expertise. These findings suggest the circumstances in which alternative social decision schemes are likely to be more effective. They also support the usefulness of conceptualizing group judgment as a weighted combination of the opinions of group members whereby the allocation of weights to members is the critical issue.Individual versus group performance has been important in social psychology since the start of the century. The central issue in this research has been the extent to which the quality of group performance is above or below that of its members. More recently, however, there has been increased emphasis on the comparative performance of interacting groups and other alternative social decision schemes, particularly composite (or staticized) groups and best-member strategies. These analyses serve both a theoretical and an applied purpose. Comparisons of individual and group performance with these and other baseline models allow attribution of differences to a series of specific factors, increasing our understanding of group processes (e.g., Einhorn, Hogarth, & Klempner, 1977). They also provide a basis for selecting the most cost-effective decision scheme in different applied settings (e.g., Libby & Blashfield, 1978).The results of studies on the comparative performance of interacting and composite groups have been somewhat conflicting. Most studies examined mean performance on a particular task or compared mean performance across a series of tasks. The considerable variation in performance among participant groups was usually treated as experimental error. As a result, differences in task characteristics were most commonly used to explain conflicting results (e.g., see Hill, 1982). No previous study has examined differences across groups within a specific context (task) to determine the characteristics of particular in-We wish to thank Phil Yetton and Richard Hackman for their comments, and Jane Butt and Sarah Bonner for their assistance on this project.