Sensitivity to statistical regularities: People (largely) follow Benford’s law

Abstract

Recent decision making research has emphasized people’s sensitivity to statistical relationships in the environment. A little-known relationship is Benford’s law, that the first digits of numbers representing many natural and human phenomena have a logarithmic distribution (Benford, 1938). Benford’s law is being used to help detect fraudulent financial data, but this assumes that people will not follow Benford’s law when generating data. In two studies I examined whether people follow Benford’s law. In Study 1 participants were given nine questions (e.g., “Length of the Indus river: km”) chosen to have a flat distribution of first-digits for correct answers. The generated distribution was close to Benford’s law. In Study 2 the results for generated data were replicated with new questions, and a selection task was also given in which participants selected from nine possible answers. Selected answers were a poor fit to Benford’s law. Taken together the results suggest that Benford’s law is a product of the way people generate responses, rather than sensitivity to the relationship itself.


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