It’s not likely many of you known about Benford’s Law, but it will surprise you especially if you happen to unwittingly bet against it.
Imagine a scenario - you’re having lunch at a counter cafe and the old guy next to you (i.e., me) says out of the blue…
I will give you 20 bucks if you open any page in that newspaper and the first number you see starts with a 7, 8, or 9. And as part of this little game, if the number starts with a 1, 2, or 3 - you have to give me just ten bucks.
Would you play that game knowing that the odds are stacked against me? It’s a two-for-one bet after all and numbers, of course, occur in the wild in even distributions, right?
Um, wrong.
Here’s a 10,000 record [data se](https://download .csv file)t of insurance information that I randomly chose for this article - download it and import it into a base. Then run the script block (included below) on these fields:
- hu_site_limit
- tiv_2011
- tiv_2012
Here are the distributions of the numbers from the insurance table. Note how predictable the beginning numbers are.
Still wanna’ bet on that newspaper game? 
With Benford’s Law, we can analyze expense records and determine if their patterns fall outside these normal distributions. If the pattern does not follow a Benford distribution, there’s a high probability that the data is contrived.
Benford’s Law Script Block
output.markdown("# Benford's Law");
// get the table name
let sourceTable = await input.tableAsync("Pick the table:");
let sourceTableName = sourceTable.name;
// get the field name
let sourceField = await input.fieldAsync("Pick the field to be analyzed:", sourceTable.id);
let sourceFieldName = sourceField.name;
// get the data set for this gallery
let result = await sourceTable.selectRecordsAsync();
let sourceRecords = result.records;
let totalValues = sourceRecords.length;
// get the record count
let recordCount = sourceRecords.length;
// iterate across all the records
let benfordCounts = {};
for (var r in sourceRecords)
{
// get the value of this record
let thisValue = sourceRecords[r].getCellValue(sourceFieldName);
// get the first digit in the number
let thisDigit = thisValue.toString()[0];
if (thisDigit != "0") {
benfordCounts[thisDigit] = (benfordCounts[thisDigit] === undefined) ? {"count" : 1, "percent" : 0.0, "chart" : ""} : {"count" : benfordCounts[thisDigit].count + 1, "percent" : 0.0, "chart" : ""};
}
}
//
// compute the percentage distribution
//
for (var i in benfordCounts)
{
// create the percentage for this digit
benfordCounts[i]["percent"] = (benfordCounts[i].count/totalValues * 100).toFixed(1);
// create the bar for this digit
benfordCounts[i]["chart"] = "█".repeat((benfordCounts[i].count/totalValues * 100).toFixed(0))
}
// output.inspect(benfordCounts);
output.table(benfordCounts);