The Wisdom of Crowds (Paperback)

The Wisdom of Crowds: Why the Many Are Smarter Than the Few and How Collective Wisdom Shapes Business, Economies, Societies and Nations, first published in 2004, is a book written by James Surowiecki about the aggregation of information in groups, resulting in decisions that, he argues, are often better than could have been made by any single member of the group. The book presents numerous case studies and anecdotes to illustrate its argument, and touches on several fields, primarily economics and psychology.
The opening anecdote relates Francis Galton's surprise that the crowd at a county fair accurately guessed the butchered or the "slaughtered and dressed" weight of an ox when their individual guesses were averaged (the average was closer to the ox's true butchered weight than the estimates of most crowd members, and also closer than any of the separate estimates made by cattle experts).
The book relates to diverse collections of independently-deciding individuals, rather than crowd psychology as traditionally understood. There are parallels with statistical sampling theory—a diverse collection of independently-deciding individuals is likely to be more representative of the universe of possible outcomes, thereby producing a better prediction.

Audio with the Author:

http://server1.sxsw.com/2006/coverage/SXSW06.INT.20060311.WisdomOfCrowds.mp3