Jelly beans

In 1987, Jack Traynor placed a jar of jellybeans in front of 56 of his students. He asked them to estimate how many beans were in the jar. The results showed that only one person in class had done better then the group estimate. There were 850 beans in the jar and the group predicted that there were 871. This was reinforced in 2007 when Michael Mauboussin presented to his Business Class (73 students) a jar of beans. The actual number in the jar was 1,116. The students guesses ranged from 250 to 4,100 - a huge range. However the collective prediction was 1,151 - pretty close. Only two people in the class were nearer. Here again, this shows that individually, people were way out, but as a group there was a much greater accuracy.

Click here to explore further

        terms and conditions:© copyright Allan Wilson 2011 all rights reserved Bookmark and Share