Overconfidence, n>1000, <1% 0,1 wrong

• 39 years (Age of MLK)

• 4187 miles (Length of Nile)

• 13 countries (Members of OPEC)

• 39 books (Books in OT)

• 2160 miles (Diameter of Moon)

• 390,000 pounds (Weight of 747)

• 1756 (Birth of Mozart)

• 645 days (Gestation of elephant)

• 5956 miles (London to Tokyo)

• 36,198 feet (Depth of sea)

Russo, Schoemaker, Decision Traps, 1989, pg 71

Previous slide

Next slide

Back to first slide

View graphic version

Here are the actual answers. Mark wrong those that lie outside the range you have put.

Now, given that there are ten questions and these are 90% confidence intervals, how many should be marked wrong on your page?

Poll group on results. Compare to other studies in which fewer than 10 of 1000 persons had 0 or 1 wrong.

We have a tendency to be overconfident in our knowledge, regardless of whether we admittedly ‘know’ the answer or not. Looked at another way, we frequently fail to predict the ‘tails’ of the future and estimate it too conservatively because we are too co