Economics and the mid-life crisis have much in common: Both dwell on foregone opportunities

C'est la vie; c'est la guerre; c'est la pomme de terre . . . . . . . . . . . . . email: jpalmer at uwo dot ca

. . . . . . . . . . .Richard Posner should be awarded the next Nobel Prize in Economics . . . . . . . . . . . .

Friday, August 12, 2005

Lying and Coin-Tossing

If 14,0o0 different people toss fair coins 9 times, roughly how many of these people would you expect to get a heads 9 times in a row? About 27 or 28? [.5**9 = 1/512] Would you deem these people "expert coin tossers" and spend more time studying their coin-tossing techniques?

Alternatively, if you have 14,000 test subjects and they all have an equal, 50% chance of detecting whether someone is lying, roughly how many of the subjects might guess right 9 times in a row? about 27 or 28?

Is all this due to randomness?

A succession of studies using tests like this have shown that most of us are not very good at spotting if someone is lying. Even people whose job it is to detect deception - police officers, FBI agents, therapists, judges, customs officers, and so on - perform, on average, little better than if they had taken a guess. ... But a few people seem to be the exceptions that prove the rule. ... In a range of studies that totalled about 14,000 people, ... The researchers identified 29 "wizards" of deception detection, who are now the subject of intensive study.
I'm sure there is much more to the studies, [in particular, I don't know the number of trials] but this snippet reminds me of people who think a given financial analyst is great because s/he got lucky 4 or 5 years in a row.
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