IN 2007 MICHAEL MAUBOUSSIN presented a big jar of jelly beans to his 73 Columbia Business School students. How many beans did they think it contained? Guesses ranged from 250 to 4,100; the actual number was 1,116. The average error was 700-a massive 62 percent-demonstrating that the students were awful estimators. Now here comes the weird part. Even with all these wildly incorrect guesses, the average guess was 1,151-just3 percent off the mark. Not only that, only two of the 73 students guessed better than this group average. So although individually everyone was woefully inaccurate, collectively the group was incredibly accurate. Was this a fluke? Hardly. The experiment was made famous in 1987 by financial economist Jack Treynor. In his case it was 850 jelly beans and 56 students. The group estimate was 2.5 percent off; only one student guessed better. The study has been repeated many times since with similar results, and this eerie effect goes beyond jelly beans.
展开▼
