Wisdom of the crowd

The wisdom of the crowd is the collective opinion of a group of individuals rather than that of a single expert.

A large group's aggregated answers to questions involving quantity estimation, general world knowledge, and spatial reasoning has generally been found to be as good as, and often better than, the answer given by any of the individuals within the group. An explanation for this phenomenon is that there is idiosyncratic noise associated with each individual judgment, and taking the average over a large number of responses will go some way toward canceling the effect of this noise. This process, while not new to the Information Age, has been pushed into the mainstream spotlight by social information sites such as , Yahoo! Answers, Quora, and other web resources that rely on human opinion.

Trial by jury can be understood as wisdom of the crowd, especially when compared to the alternative, trial by a judge, the single expert. In politics, sometimes sortition is held as an example of what wisdom of the crowd would look like. Decision-making would happen by a diverse group instead of by a fairly homogenous political group or party.

Research within cognitive science has sought to model the relationship between wisdom of the crowd effects and individual cognition.

In the context of wisdom of the crowd, the term "crowd" takes on a broad meaning. One definition characterizes a crowd as a group of people amassed by an open call for participation. While crowds are often leveraged in online applications, they can also be utilized in offline contexts. In some cases, members of a crowd may be offered monetary incentives for participation. Certain applications of "wisdom of the crowd", such as jury duty in the United States, mandate crowd participation.

Aristotle is credited as the first person to write about the 'Wisdom of the crowd' in his work titled 'Politics'.

The classic wisdom-of-the-crowds finding involves point estimation of a continuous quantity. At a 1906 country fair in Plymouth, 800 people participated in a contest to estimate the weight of a slaughtered and dressed ox. Statistician Francis Galton observed that the median guess, 1207 pounds, was accurate within 1% of the true weight of 1198 pounds. This has contributed to the insight in cognitive science that a crowd's individual judgments can be modeled as a probability distribution of responses with the median centered near the true value of the quantity to be estimated.

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