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Cuchulainn
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Posts: 20254
Joined: July 16th, 2004, 7:38 am
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Benford's Law and cooking the Data

December 17th, 2020, 7:43 pm

Let'e pretend we have received a workbreakdown WBS estimate (in Euros, not manhours!) of a project consisting of 9 activities + cost per activity

Act, cost
=======
1, 2950
2, 1550
3, 2950
4, 550
5, 2650
6,  350
7, 450
8, 550
9, 750
==
Total 12750 (start point?? start with the end in mInd).

Has this data been manipulated? e.g. according to Benford, '5' should have a frequency in first digit  of 7.9% but in our case it is 35%.

Does this require further inspection?


// a more generic example
0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811
 
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bearish
Posts: 5188
Joined: February 3rd, 2011, 2:19 pm

Re: Benford's Law and cooking the Data

December 17th, 2020, 9:05 pm

No. Not only do you have an exceedingly small sample, but the ratio of the largest to the smallest number is less than 10, so you fail the (soft, I guess) criterion for Benford’s Law to apply that the distribution spans several orders of magnitude.