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How many coins?

posted by Jason Kottke   Oct 27, 2008

Earlier this evening, I needed to take some coins that had been piling up to the Coinstar machine. Before I left, I uploaded a photo of the coin bags to Flickr and queried the masses: how much money in the bags?

How did the crowd do? Certainly not as well as the villagers at the 1906 livestock fair visited by Francis Galton.

In 1906 Galton visited a livestock fair and stumbled upon an intriguing contest. An ox was on display, and the villagers were invited to guess the animal’s weight after it was slaughtered and dressed. Nearly 800 gave it a go and, not surprisingly, not one hit the exact mark: 1,198 pounds. Astonishingly, however, the median of those 800 guesses came close — very close indeed. It was 1,208 pounds.

Nate Silver I am not, but after some rudimentary statistical analysis on the coin guesses, it was clear that the mean ($193.88) and median ($171.73) were both way off from the actual value ($426.55). That scatterplot is brutal…there are only a handful of guesses in the right area. But the best guess by a single individual was just 76 cents off.

To be fair, the crowd was likely misinformed. It’s difficult to tell from that photo how fat those bags were — they were bulging — and how many quarters there were.

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