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Oldie but oldie! Used for detecting tax return irregularities:
people dream up way to many 5's too few ones.
[From an ECN on line piece....]
Brian W
Dr. Benford discovered, in a huge assortment of number
sequences -- random samples from a day's stock quotations, a
tournament's tennis scores, the numbers on the front page of
The New York Times, the populations of towns, electricity
bills in the Solomon Islands, the molecular weights of
compounds the half-lives of radioactive atoms and much more
-- [something unexpected.]
Given a string of at least four numbers sampled from one or
more of these sets of data, the chance that the first digit
will be 1 is not one in nine, as many people would imagine;
according to Benford's Law, it is
30.1 percent, or nearly one in three. The chance that the
first number in the string will be 2 is only 17.6 percent,
and the probabilities that successive numbers will be the
first digit decline smoothly up to 9, which has only a 4.6
percent chance.
A strange feature of these probabilities is that they are
"scale invariant" and "base invariant."