Ask the Slot Expert: Is there proof that slot machines are not rigged?

By John Robison, Slot Expert™
19 August 2015

I was wondering about video poker machines and blackjack machines. Is there proof that they are not rigged somehow?

In other words, the RNG is programmed to do its normal thing but, say, every 100 hands if it lands on a certain number that it somehow deletes the pick or changes it?

A number of years ago at New York-New York Hotel & Casino, I was playing video poker and video blackjack and could not win anything. I played for about a half hour until I decided to leave. To me it seemed like it was fixed. I often had 18, 19, 20 and the machine was getting either a tie (push) and or a blackjack.

This is analogous to trying to prove that a conspiracy does not exist. It's easy to show that a conspiracy exists, but very difficult to prove that one does not exist.

On second thought, maybe proving that slots are not rigged is not so similar after all. Every slot machine on every slot floor in the United States has been approved by some slot testing lab, whether it's the state's own lab or Gaming Laboratories International.

The testing lab ensures that the output of the RNG passes a number of tests of randomness. It ensures that each game program operates properly -- that is, every winning combination on the pay table can be made on every spin or hand and the game returns the percentage claimed on its PAR sheet.

After a game has been approved for a jurisdiction and placed on the slot floor, regulators may make random inspections to ensure that a slot machine has not been rigged and that the program the regulators approved is running in the slot machine without any alterations.

This is how Ron Harris was able to rig slot machines in Las Vegas. He worked for the Nevada Gaming Commission. He reprogrammed the device used to verify that the game program stored in the chips in a slot machines has not been altered to actually alter the program in the chips. In other words, the procedure used to verify that the program has not been changed changed the program.

I know of another instance of a rigged program in machines. Many years ago, a slot route operator, which placed machines in bars, gas stations and convenience stores, altered the programming in its video poker machines to make royal flushes less likely. The alteration was discovered and the company is no longer in business.

More proof is in slot regulations. Slot regulations prohibit changing the result determined by the output from the RNG. Slot regulations in Nevada and New Jersey, which are the models for most jurisdiction's regulations, require that the result determined by the output from the RNG must be displayed without any alteration. This regulation was written about 30 years ago to disallow the so-called "secondary decision" in machines from Universal. The program in these machines did not display the outcome determined by the RNG for losing spins. Instead, it selected from a table of exciting losing spin combinations. So instead of seeing something like blank-symbol-symbol land on the payline, players saw symbol-symbol-blank.

Finally, it's not unusual to have losing streaks -- even long losing streaks -- on machines that are not rigged and are operating correctly. I play a lot of 9/6 Jacks or Better. The hit frequency is almost 50%, yet I've had many instances of getting 22 to 25 plays from a $100 buy-in on a dollar machine. Half an hour of play is just far too small a sample to make any conclusion about the fairness of the machine. It is a sufficient sample, however, to say that you had a run of bad luck.



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Send your slot and video poker questions to John Robison, Slot Expert™, at slotexpert@slotexpert.com. Because of the volume of mail I receive, I regret that I can't reply to every question.

Copyright © John Robison. Slot Expert and Ask the Slot Expert are trademarks of John Robison.
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