The kind of group you want to belong to: Effects of group structure on group accuracy.

There has been much interest in group judgment and the so-called 'wisdom of crowds'. In many real world contexts, members of groups not only share a dependence on external sources of information, but they also communicate with one another, thus introducing correlations among their responses that can diminish collective accuracy. This has long been known, but it has-to date-not been examined to what extent different kinds of communication networks may give rise to systematically different effects on accuracy. We argue that equations that relate group accuracy, individual accuracy, and group diversity (see Hogarth, 1978; Page, 2007) are useful theoretical tools for understanding group performance in the context of research on group structure. In particular, these equations may serve to identify the kind of group structures that improve individual accuracy without thereby excessively diminishing diversity so that the net positive effect is an improvement even on the level of collective accuracy. Two experiments are reported where two structures (the complete network and a small world network) are investigated from this perspective. It is demonstrated that the more constrained network (the small world network) outperforms the network with a free flow of information.