What a Truly Fair Lottery Process Looks Like

Thursday, December 2, 2010
Everyone loves prizes. If you want to give an "Around the World Trip" prize to one person, you could use a fun lottery machine and draw the number in front of a crowd. But if your prize is "100 iPads for 100 winners," you'll have to think of something a little more sophisticated.

You'll want to be able to tell anyone that it was a fair lottery. If you merely say you used a random draw by computer, some may still harbor doubts concerning transcription mistakes or a few dishonestly pulled strings behind closed doors. If possible, we'd want a process that has a low possibility of internal cheating, and also prevents mistakes and redo's.

Today many prize entries are made by webforms, so the list of entries are often managed as Excel sheets. First we make a complete list of entries by excluding unqualified email addresses and double-entries (1–3). After the list is completed, the accounting department is notified only the total number of entries and number of winners, so that they can prepare a list of winning numbers by random number generation (4). Of course, the actual list of entries is never shown to accounting; in other words, unless there is a conspiracy between the two department heads, there can be no bias in the winner list. And just in case, the time each task is completed is recorded and available in the workflow system, so any dishonest redo's should be caught easily.

Here's an even safer workflow, where the CEO decides a "magic number" which is calculated with all winning numbers.