EXAMPLE 4.12

Benford’s law. Faked numbers in tax returns, payment records, invoices, expense account claims, and many other settings often display patterns that aren’t present in legitimate records. Some patterns, such as too many round numbers, are obvious and easily avoided by a clever crook. Others are more subtle. It is a striking fact that the first digits of numbers in legitimate records often follow a distribution known as Benford’s lawBenford’s law. Here it is (note that a first digit can’t be 0):³