Numbers follow a surprising law of digits

May 11, 2007 13:57 GMT  ·  By
This graph shows several examples of data sets from the Spaniard National Institute of Statistics that follow Benford?s logarithmic law. Data from the lottery, however, is random and uniform.
   This graph shows several examples of data sets from the Spaniard National Institute of Statistics that follow Benford?s logarithmic law. Data from the lottery, however, is random and uniform.

Number 1 is very frequently used around the world. That wouldn't be much of a curiosity, if you knew all the fields it appears in.

It's the most commonly found figure in groups as disparate as populations, death rates, physical and chemical constants, baseball statistics, the half-lives of radioactive isotopes, answers in a physics book, prime numbers and Fibonacci numbers.

Many people would intuitively say that it's because 1 has to represent the first notion or position in many situations. Well, here are some figures: 33% of all country areas begin to contain the figure 1, so do national birth rates, CPI variations, national population and housing censuses and even house addresses.

The other figures, up to 9, follow an interesting appearance pattern, called Benford's law, or the first-digit law. This says that in lists of numbers from many real-life sources of data, the leading digit is 1 almost one third of the time and larger numbers occur as the leading digit with less and less frequency as they grow in magnitude, to the point that 9 is the first digit less than one time in twenty.

Scientists Jes■s Torres, Sonsoles Fern?ndez, Antonio Gamero, and Antonio Sola from the Universidad de Cordoba also call the feature surprising and they published a book called How do numbers begin? (The first digit law) in which they bring historical arguments that support the theory about the occurrence of figures.

"Nowadays there are many theoretical results about the law, but some points remain in darkness," said Torres. "Why do some numerical sets, like universal physical constants, follow the law so well? We need to know not only mathematical reasons for the law, but also characterize this set of experimental data. For example, what are their points of contact? Where they come from? Apparently, they are independent.

I hope the general necessary and sufficient conditions will be discovered in the future-many people are interested in the law, especially economists-but I also know it could be not possible ever," he added.

Even the discovery of the law is strange, as both Frank Benford, who discovered it in 1935 and Simon Newcomb, who discovered the law in 1881, found the algorithms while flipping through pages of a book of logarithmic tables, when they observed that the first pages were dirtier than the other, which meant that other scientists also preferred quantities beginning with the number one in their various applications.