Jellybeans
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.
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