DATA MINING
Desktop Survival Guide by Graham Williams |
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Other Digits |
Benford's Law primarily applies to the first digit of the numbers. A similar, but much less strong, law also applies to the second, third and fourth digits. A common mathematical formula has been developed that generalises the distribution for the first, and the distributions converge to a flat distribution the further we go.
For the second digit, for example, the expected frequency of the digit 1 is 11.4%, compared to the digit 2's 10.9%. As we proceed to the third and fourth and so on, each has an expected frequency pretty close to 0.1 (or 10%), indicating they are all generally equally likely.
Even though the distributions become flat, it can still be useful to plot the actual distribution in order to explore for oddities in our data. Rattle allows us to plot up to the ninth digit.