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Best of John Robison

Gaming Guru

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Ask The Slot Expert

5 April 2001

Dear John,

Are online video poker machines on one main computer? I'm wondering whether long-term playing is an advantage or if the cards are bad to give it a rest and come back later hoping that the bad streak was played through by someone else. I have played many hours and sometimes it seems I win a lot to suck me in, and then the computer proceeds to take my winnings and more.

Plus do you know how the odds are on keno. I love to play, but it's hard to win anything good.

It doesn't make any difference whether you stop or continue playing. Your odds of getting a good hand are the same regardless of what has happened in the past to you or any other player.

Long-term playing is really only an advantage when you're playing a machine that pays back more than 100%. A less than 100% machine will, in the long run, eventually win back any money you've won from it.

The odds on keno depend upon how many numbers you play, the number of numbers drawn, and the number of numbers in the pool. Generally, keno is one of the worst bets in the house.

Best of luck in and out of the casinos!
John

Hi John,

Got your report, The Slot Expert's Guide to Playing Slots. Great stuff. Learned a lot from it.

A question, Mr. Expert, regarding the number of spins a manufacturer runs a slot through to determine percentage payback.

Steve Early says l million. You say l0 million. I've also seen it put as hundreds of thousands. Some sources even put a time limit on percentage determination: from 6 months to a year.

Are there variables in here somewhere?

Sincerely,
Larry

Dear Larry,

Thanks for the kind words about The Slot Expert's Guide.

You asked a great question. It's one I've wanted to set people straight about for some time.

How many spins does a manufacturer play on a slot machine to determine its payback? ZERO.

There's no reason to play the game to calculate the payback. The manufacturer knows how times each symbol appears on each virtual reel. With that data, they can calculate the probability for each winning combination to land on the payline. Multiply by the value of each winning combination and add up. Divide the total by the total number of combinations possible times the number of coins played and you have the payback.

Manufacturers usually have to provide confidence intervals to the casinos and regulatory agencies. These intervals tell the range the actual payback on the machine is expected to fall in after a certain number of spins. Machines that have paid back a percentage that falls outside the intervals may be malfunctioning or may be the targets of cheaters.

I'm not sure in what context I said 10 million spins. It's true that it may take 10 million spins for the range that the actual payback falls in (the confidence interval, that is) to be below, say, 1/2 percentage point on either side of the theoretical. But the only information needed to calculate the hit frequency, payback, and confidence intervals are the paytable and the layouts of the virtual reels.

Any sort of a time limit is nonsense. The only thing that matters in the confidence interval is the number of spins.

It might make sense in a generality to say that most machines get enough play in six months to be in a certain range around their theoretical paybacks. And players understand a timeframe. They have no concept of how long it takes for a machine to get a million plays. But specifying a timeframe gets some people to think that machines track how long they've been in operation and get looser or tighter in order to pay back the appropriate amount.

A lab may "spin" the reels millions of times to test the performance of the RNG. But they don't actually play the machine. They connect their testing computer to a special connector in the slot machine and put the machine in a special test mode that has it send the output of the RNG to the testing computer.

Best of luck in and out of the casinos!
John


Send your slot and video poker questions to John Robison, Slot Expert, at slotexpert@home.com.


For more information about slots and video poker, we recommend:

The Slot Expert's Guide to Playing Slots by John Robison
Break the One-Armed Bandits! by Frank Scoblete
Victory at Video Poker and Video Craps, Keno and Blackjack! by Frank Scoblete
Slot Conquest Audio Cassette Tape (60 minutes) with Frank Scoblete
Winning Strategies at Slots & Video Poker! Video tape hosted by Academy Award Winner James Coburn, Written by Frank Scoblete
The Slot Machine Answer Book by John Grochowski
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