Benford's Law
Start with a uniform distribution in which leading digits one through nine are equally likely.
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Principles and uses
Explore leading-digit frequencies that follow a Benford distribution in suitable datasets.
The leading-digit probability is log₁₀(1+1/d).
The pattern occurs in some data spanning several orders of magnitude, but not all datasets. Compare Fibonacci numbers and powers in this example.
Use it as one anomaly signal after checking applicability. Deviations alone do not establish error or manipulation.