Use Benford's Law To Catch (Or Pull Off) Fake Numbers

How can accountants, election inspectors, and academic reviewers know at a glance that your numbers are bunk? They use Benford's Law, which suggests number distribution is less random than expected. Roughly 30 percent of numbers, for example, should start with 1.

Benford's Law has been around for some time, but its application in computer analysis of data sets, and human understanding of what numbers should look like, is becoming more and more important in an era where numbers, prices and other data fly by at increasing speed—and some of them seem so easy to fake.

Commenter and blogger Steve Mould posts about Benford's law and how it applies to cheating, and cheating detection. He poses the hypothetical: What are the chances of any number starting with any number, one through nine?

Well you're choosing at random so the chance of your number starting with any one of those 9 digits must be 1 in 9. That's about 11%.

The surprising result of Frank Benford's work is that the number you just plucked from the universe is far more likely to start with a 1 (about 30.1%) and very unlikely to start with a 9 (about 4.6%). And there's a sliding scale for the digits in between.

It's a great read for understanding the quirks in "random" numbers. And it explains why badly faked tax returns are so easy to catch, and how you might make your own numbers believable for presentation demonstrations and the like.

How to cheat with Frank Benford [SHIFT_beep via #tips]


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