Dr. Nigrini found that it probably contained some rounded-off estimates rather than precise numbers, but he concluded that his test did not reveal any fraud. The fit of number sets with Benford's Law is not infallible. In a lottery someone simply pulls a series of balls out of a jar, or something like that. The numbers they represent are uniformly distributed, every number has an equal chance, and Benford's Law does not apply to uniform distributions. Another problem Dr. Nigrini acknowledges is that some of his tests may turn up too many false positives.
Various anomalies having nothing to do with fraud can appear for innocent reasons.
For example, the double digit 24 often turns up in analyses of corporate accounting, biasing the data, causing it to diverge from Benford's Law patterns and sometimes arousing suspicion wrongly, Dr. Nigrini said. But the cause is not real fraud, just a little shaving. That's why we see so many 24's. A variant of his Benford's Law software already in use, he said, could spot any significant change in a company's accounting figures between 1999 and 2000, thereby detecting a computer problem that might otherwise go unnoticed. For me, Benford is a great hero.