A recent post over at the Marginal revolution on Benford’s law was very educational. Here is a quote….

In many data series a surprising number of entries begin with the number 1, and the number 2 is also more common than a random distribution might suggest. This is called Benford’s Law. For instance about one third of all house numbers start with one. That may be a quirk of bureaucratic numbering psychology, but the principle also applies to the Dow Jones index history, size of files stored on a PC, the length of the world’s rivers, and the numbers in newspapers’ front page headlines. It does not apply to lottery-winning numbers, see the graph at the above link.

The law only applies if you are measuring or counting something. That is why it does not apply to lottery numbers. The interesting thing about this law is how it can be used to detect various kinds of fraud. Apparently, it is very hard to fake numbers (for financial results or voters tallies) and still comply with Benford’s law.