help for ^benford^ (Nikos Askitas)Apply Benford's Law to a variable ---------------------------------------------------

^benford^ varname [if] [in]

Description -----------

^benford^ reads in the values of a variable and returns a 4 column table: Column 1 contains the digits 1 through 9, column 2 contains the total number of values in the variable starting with that digit, Column 3 contains the percentage Column 2 represents and Column 4 is what benfords law expects. So the closer Columns 3 and 4 are the more your numbers conform to Benfords law.

Remarks -------

^benford^ just presents the measurements in a form which makes it easy to inspe > ct. Both knowing whether your variable should conform to Benford's law or not and w > hether the results suggest your dataset is authentic or rigged is up to you. The autho > r is happy to point the user to N. J. Cox's ^firstdigit^ module for a more comprehensive t > reatment as well as acknowledge a masterful rewrite of the first - a more pedestrian - v > ersion.

Examples -------- While developing I played with auto.dta which is both too small and contains no > variables which should conform to Benford's law. So to just see it work you can > do:

. ^sysuse auto.dta^ . ^benford price^

The dataset http://www.stata-press.com/data/r9/census6.dta contains variables w > hich are suitable for Benford's Law. Although it is too small to get any reliable distribution it still shows a relative conformity.

. ^ use http://www.stata-press.com/data/r9/census6.dta^ . ^ benford pop^

will return:

Digit Count Frequency Benford ----------------------------------------- 1 10 20.00 30.10 2 8 16.00 17.60 3 5 10.00 12.50 4 10 20.00 9.70 5 7 14.00 7.90 6 2 4.00 6.70 7 2 4.00 5.80 8 1 2.00 5.10 9 6 12.00 4.60 ------------------------------------------

Author ------ Dr Nikos Askitas, IZA, Bonn, Germany. Email: ^nikos@@iza.org^