Title: Aggregated knowledge from a small number of debates outperforms the wisdom of large crowds,
Abstract: The aggregation of many independent estimates can outperform the most
accurate individual judgment. This centenarian finding, popularly known as the
wisdom of crowds, has been applied to problems ranging from the diagnosis of
cancer to financial forecasting. It is widely believed that social influence
undermines collective wisdom by reducing the diversity of opinions within the
crowd. Here, we show that if a large crowd is structured in small independent
groups, deliberation and social influence within groups improve the crowd's
collective accuracy. We asked a live crowd (N=5180) to respond to
general-knowledge questions (e.g., what is the height of the Eiffel Tower?).
Participants first answered individually, then deliberated and made consensus
decisions in groups of five, and finally provided revised individual estimates.
We found that averaging consensus decisions was substantially more accurate
than aggregating the initial independent opinions. Remarkably, combining as few
as four consensus choices outperformed the wisdom of thousands of individuals.