Derren Brown abuses The Wisdom of Crowds

One of Derren Brown's recent Events was to 'correctly' guess the winning six number of the UK National Lottery. Brown attributed his success to the wisdom of crowds. On his website he has the following piece

Crowd behaviour is often associated with irrationality. Crowds form mobs and cults. They panic and the herd instinct is often wrong and easily swayed. At least that is the common perception. But scientist and polymath Francis Galton discovered that not all crowd behaviour was negative. Indeed he found that if you asked enough people the same question, they might come up with better answers than even the experts.

It was in 1906 that Galton made his discovery of what is known as the wisdom of crowds. He attended a farmers' fair in Plymouth where he was intrigued by a weight guessing contest. The goal was to guess the weight of an ox when it was butchered and dressed. Around 800 people entered the contest and wrote their guesses on tickets. The person who guessed closest to the butchered weight of the ox won a prize.

After the contest Galton took the tickets and ran a statistical analysis on them. He discovered that the average guess of all the entrants was remarkably close to the actual weight of the butchered ox. In fact it was under by only 1lb for an ox that weighed 1,198 lbs. This collective guess was not only better than the actual winner of the contest but also better than the guesses made by cattle experts at the fair. It seemed that democracy of thought could produce amazing results.

However, to benefit from the wisdom of crowds several conditions must be in place. First each individual member of the crowd must have their own independent source of information. Second they must make individual decisions and not be swayed by the decisions of those around them. And third, there must be a mechanism in place that can collate these diverse opinions.

Internet search engines are a good example of the wisdom of crowds in action. It is the reason the pages you search for come up near the top of the search engine list.

In general terms the more people are linking to a page and the more popular it is the higher it comes. Another highly visible example of crowd decision making can be found in the television game show Who Wants To Be A Millionaire. When the player does not know which one of four answers is correct, they can ask the audience. Each member of the audience makes a separate and individual vote for the answer they favour. These votes are then collected and the results displayed. Often it is obvious from the result that one particular answer has found favour. And that is the one the player generally goes along with. In 95% of cases it is correct.