Benford's Law and Detecting Bogus Data Sets

"Fun (and Fraud Detection) with Benford's Law"
Kirix (July 22, 2008)

"Benford's law is one of those things your high school math teacher would break out on a slow, rainy day when the students’ attention span was even lower than usual.

"He'd start out by asking the class to look at the leading digits in a list of numbers and then predict how many times each leading digit would appear first in the list. The students would make some guesses and eventually come to the consensus that the probability would be pretty close — about 11% each..."

"...Boiling it down, this means that for almost any naturally-occurring data set, the number 1 will appear first about 30% of the time. And, by naturally occuring, this can mean check amounts or stock prices or website statistics. Non-naturally occurring data would be pre-assigned numbers like postal codes or UPC numbers...."

This post is an example of why I don't think that mathematics in intrinsically boring.

There's an instructional video, quite a few links - and enough text in that post to tell you what Benford's Law is, and how to use it.

A pretty good resource.