Benford Law Statistics for Google Docs https://docs.google.com/spreadsheet/ccc?key=0Al_D4zS2T4QodHhjM0JxejRKZWpWTWVKUUxISVlfTnc

Benford.gs

/*
Google Spreadsheet custom functions for Benford Law statistics

author : Philippe Guglielmetti aka Dr. Goulu
contact: drgoulu@gmailcom
license: LGPL
 */

function sum(a, b) { return a + b; } // not predefined ?

function log10 (arg) { return Math.log(arg) / 2.302585092994046;} // Math.LN10

function Benford(range, digit,n) {
  // returns the fraction of cells in range that have their n-th digit equal to digit
  // see http://en.wikipedia.org/wiki/Benford's_law
  digit=String(digit);
  n = typeof n !== 'undefined' ? n-1 : 0;
  var process = function(cell) { return String(cell)[n]==digit ? 1:0;}  
  var values = range.map(process);
  return values.reduce(sum, 0)/range.length;
}

function BenfordLaw(i,n){
 //return probability of n-th digit to be a i according to Benford law
  n = typeof n !== 'undefined' ? n : 1;
  var s = 0;
  if (n>1 | i>0) {
    for (k=Math.floor(Math.pow(10,n-2)); k<Math.pow(10,n-1); k++) {
      s+=log10(1+1/(10*k+i))
    }
  }
  return s;
}

function Chi2(data,model){
  result=0;
  for (i in data) {
    result=result+Math.pow(data[i]-model[i],2)/model[i];
  }
  return result;
}

function Chi2Benford(data,n) {
  n = typeof n !== 'undefined' ? n : 1;
  var s=data.reduce(sum, 0);
  var b=new Array();
  var d=new Array();
  for (i=1; i<10; i++) {
    b[i]=BenfordLaw(i,n);
    d[i]=Benford(data,i,n);
  }
  return Chi2(d,b);
}

function main() {
  Chi2Benford([3,2,1],1);
}