I am trying to find some use of the Benford’s law in testing.
“Benford’s law, also called the first-digit law, states that in lists of numbers from many (but not all) real-life sources of data, the leading digit is distributed in a specific, non-uniform way. According to this law, the first digit is 1 about 30% of the time, and larger digits occur as the leading digit with lower and lower frequency, to the point where 9 as a first digit occurs less than 5% of the time. This distribution of first digits is the same as the widths of gridlines on the logarithmic scale. Benford’s law also gives the expected distribution for digits beyond the first, which approach a uniform distribution as the digit place goes to the right.” –wikipedia
I thought I found a solution when googling by “1”,”2”,”3” or “one”, “two”, “three” or using even quotes for the same searches to be the exact match. But then I realized that I can hit a search result containing “two hundred and twenty one” when searching for “one” so I am very far from applying the principle in a relevant way.
Well it seems to make some sense though based on the graph, so maybe it’s some sort of applicable variation.
But let’s try something more relevant:
List of countries by number of mobile phones in use
http://en.wikipedia.org/wiki/List_of_countries_by_number_of_mobile_phones_in_use
| 1 | 1,010,000,000 | |
| 2 | 911,168,193 | |
| 3 | 327,577,529 | |
| 4 | 250,100,000 | |
| 5 | 245,200,000 | |
| 6 | 224,260,000 | |
| 7 | 121,246,700 | |
| 8 | 114,610,000 | |
| 9 | 107,000,000 | |
| 10 | 90,583,306 | |
| 11 | 88,797,186 | |
| 12 | 88,580,000 | |
| 13 | 86,550,000 | |
| 14 | 86,000,000 | |
| 15 | 75,750,000 | |
| 16 | 72,300,000 | |
| 17 | 71,460,000 | |
| 18 | 66,000,000 | |
| 19 | 58,730,000 | |
| 20 | 69,000,000 | |
| 21 | 68,000,000 | |
| 22 | 54,377,000 | |
| 23 | 52,510,000 | |
| 23 | 50,890,000 | |
| 25 | 50,409,800 | |
| 26 | 47,153,200 | |
| 27 | 46,147,937 | |
| 28 | 42,300,000 | |
| 29 | 33,000,000 | |
| 30 | 27,400,000 | |
| 31 | 27,100,000 | |
| 32 | 25,412,000 | |
| 33 | 22,800,000 | |
| 34 | 25,543,862 | |
| 35 | 27,050,000 | |
| 36 | 20,000,000 | |
| 37 | 21,260,000 | |
| 38 | 46,000,000 | |
| 39 | 30,379,000 | |
| 40 | 21,000,000 | |
| 41 | 17,571,895 | |
| 42 | 17,359,312 | |
| 43 | 15,900,000 | |
| 44 | 14,500,000 | |
| 45 | 14,240,670 | |
| 46 | 13,264,896 | |
| 47 | 11,822,000 | |
| 48 | 11,833,000 | |
| 49 | 11,540,040 | |
| 50 | 10,655,000 | |
| 51 | 9,319,000 | |
| 52 | 7,000,000 | |
| 53 | 7,000,000 | |
| 54 | 6,010,000 | |
| 55 | 7,289,000 | |
| 56 | 4,620,000 | |
| 57 | 1,982,000 | |
| 58 | 2,720,000 | |
| 59 | 4,960,000 | |
| 60 | 1,294,167 | |
| 61 | 1,000,000 |
Starting digits for the number of mobile phones in this list:
| Starting digit | Occurrences | Percent |
| 1 | 17 | 27 |
| 2 | 13 | 21 |
| 3 | 3 | 4 |
| 4 | 6 | 9 |
| 5 | 5 | 8 |
| 6 | 4 | 6 |
| 7 | 6 | 9 |
| 8 | 4 | 6 |
| 9 | 3 | 4 |
Considering that the data sample has only 61 records and for the first digits we have a success, I think its “relevant enough” and the example is “acceptable”.
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