Slashdot Mirror
Statistician Cracks Code For Lottery Tickets
Hugh Pickens writes writes "Lottery Post has an interesting story about Mohan Srivastava, an MIT educated statistician who became intrigued by a particular type of scratch-off lottery ticket called an extended-play game — sometimes referred to as a baited hook — that has a tic-tac-toe grid of visible numbers that looks like a miniature spreadsheet. Srivastava discovered a defect in the game: The visible numbers turned out to reveal essential information about the digits hidden under the latex coating. Nothing needed to be scratched off — the ticket could be cracked if you figured out the secret code. Srivastava's fundamental insight was that the apparent randomness of the scratch ticket was just a facade, a mathematical lie because the software that generates the tickets has to precisely control the number of winners while still appearing random. 'It wasn't that hard,' says Srivastava. 'I do the same kind of math all day long.'"
The same article appeared in Feb 2011 issue of Wired even though Lottery Post doesn't seem to go out of its way to attribute the author and cite the issue properly.
from TFA:
"Once I worked out how much money I could make if this was my full-time job, I got a lot less excited," Srivastava says. "I'd have to travel from store to store and spend 45 seconds cracking each card. I estimated that I could expect to make about $600 a day. That's not bad. But to be honest, I make more as a consultant, and I find consulting to be a lot more interesting than scratch lottery tickets."
RTFA
"Lots of people buy lottery tickets in bulk to give away as prizes for contests," he says. He asked several Toronto retailers if they would object to him buying tickets and then exchanging the unused, unscratched tickets. "Everybody said that would be totally fine. Nobody was even a tiny bit suspicious," he says. "Why not? Because they all assumed the games are unbreakable. So what I would try to do is buy up lots of tickets, run them through my scanning machine, and then try to return the unscratched losers.
The problem is that he reverse engineered their deterministic process for generating winners and losers and then was able to pick out the winning cards based on the partial information they revealed. The order in which they are printed doesn't really matter. Given any random subset of the cards he could pick the winners out of them at a much higher % than he should have been able to if they were actually random.
... :(
Sounds to me like they should figure the game out in such a way that a real random number generator will generate winners and losers at the desired rates on average and then just rely on the law of averages / large numbers to give them their desired take.
Forgot to login, sorry for the dup
He comments on the issue in TFA:
"I remember thinking, I'm gonna be rich! I'm gonna plunder the lottery!" he says. However, these grandiose dreams soon gave way to more practical concerns. "Once I worked out how much money I could make if this was my full-time job, I got a lot less excited," Srivastava says. "I'd have to travel from store to store and spend 45 seconds cracking each card. I estimated that I could expect to make about $600 a day. That's not bad. But to be honest, I make more as a consultant, and I find consulting to be a lot more interesting than scratch lottery tickets."
Seems like a decent, down-to-earth guy; he's pretty well off already (six figure salary, if he's making more than $600/day), so I'm sure it's a prospect that was easier for him to forego than most, but it looks like he's got a good balance between the comfort of money and enjoyment of his work.
Yet again, Slashdot links to some parastic site that copied the original story rather than the source: http://www.wired.com/magazine/2011/01/ff_lottery/all/1.