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# More on slot machine progressives

9 February 2009

Hi. I disagree of what you said. Most of the machines work according to what you've said. I.e., each outcome is random and independent.

But for some jackpots, operators/manufacturers could set it in such a way using the following way:

The jackpot'll be hit at most in x number of games. I.e., the probability of hitting the jackpot increases with each game played if the jackpot is not hit. But operators would not reveal how many games and could change this number from time to time and thus in a way control either the win % or average jackpot amount struck.

For example, say, every bet on average is for 10 cents. One million strokes would produce a turnover of \$100,000. If the operator chooses to win 4% of that amount and gives 1% to the jackpot, after one million strokes, if no one hits the jackpot (suppose the staring jackpot base is \$0), the jackpot would stand at \$1,000. Now notice that it does not matter to the operator what the number of maximum games is chosen before the jackpot is hit, it still wins 4% (other than the different demand due to different configurations). The number, however, would determine the average amount of jackpot struck. Thus, I can set it using different mathematical functions. An easy example: Suppose the operator chooses 1 million as the maximum number of games before the jackpot is hit. Then a simple formula to use for probability of hitting the jackpot is 1/n where n is 1,000,000 minus the games that have been played.

This kind of machines exist in a lot of casinos around the world, but casinos would not let anyone know which ones. The reason is simple. People who know how to calculate can choose to use wait-and-see approach, i.e., waiting for the jackpots to reach a certain amount before they play to give them positive expected value.

What you've described is technically possible. After all, slots are just computer systems at heart and we could program them in many ways.

Although we could program them in many ways, slot-enabling statutes in the United States severely limit our options. In fact, we have only one option for the reel-spinning game. The program will use one or more numbers from the RNG to choose one virtual stop on each virtual reel, which cannot be changed without changing a chip on the logic board. The virtual stops are mapped to physical stops on the physical reel. The probability of landing a combination on the payline is determined solely by the number of times the symbols in the combination appear on the virtual reels. There is no other influence on the probabilities.

Given these statutory requirements, the process you described cannot be done in the U.S. because the virtual reel layouts cannot be changed on the fly. Abroad is another matter. I'm not familiar with what is and isn't allowed in other countries.

Now, let me ask you a question. Why would a casino want a machine that operates the way you described? Why would they want a machine that is guaranteed to pay its jackpot after a certain number of spins and then not publicize that fact? Wouldn't the machine get even more play if the jackpot were allowed to grow beyond the guarantee? Lottery sales and wide-area-progressive slot play increase as their jackpots increase. You even wrote that "it doesn't matter to the operator what the maximum number of games is...."

And one more question. Which manufacturers build machines that operate the way you described?

Best of luck in and out of the casinos,
John

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

John Robison

John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

#### Books by John Robison:

The Slot Expert's Guide to Playing Slots
John Robison
John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

#### Books by John Robison:

The Slot Expert's Guide to Playing Slots