Using Benford's law to detect data error and fraud : an examination of companies listed on the Johannesburg Stock Exchange

Abstract

Accounting numbers generally obey a mathematical law called Benford's Law, and this outcome is so unexpected that manipulators of information generally fail to observe the law. Armed with this knowledge, it becomes possible to detect the occurrence of accounting data that are presented fraudulently. However, the law also allows for the possibility of detecting instances where data are presented containing errors. Given this backdrop, this paper uses data drawn from companies listed on the Johannesburg Stock Exchange to test the hypothesis that Benford's Law can be used to identify false or fraudulent reporting of accounting data. The results support the argument that Benford's Law can be used effectively to detect accounting error and fraud. Accordingly, the findings are of particular relevance to auditors, shareholders, financial analysts, investment managers, private investors and other users of publicly reported accounting data, such as the revenue services.