Newsletter Signup
Stay informed with the
NEW Casino City Times newsletter!
Recent Articles
Best of John Robison

Gaming Guru

author's picture

Stopping the Spin, Cash Encounters

16 February 2004

By John Robison

Hi, John,

Enjoy reading your column.

I have a question for you. Has anyone measured the results of one player who continually stops a slot machine against a player who always lets the slot finish its roll?

We have seen folks who continually press the "stop spin" button and they seem to do okay.

Is it possible to alter the result of the mahine by stopping the spin or has the outcome been decided once the coins have been entered?

Thanks in advance and keep up the good work.


Dear Sibilius,

Your last statement is correct. The result is determined when you start the game. The only thing that pressing the Stop Spin button does is cut out the spinning of the reels--the show, as they call it in the industry. The result is the same as if you didn't hit the Stop Spin button.

Best of luck in and out of the casinos,

Hi, John,

I was playing this past weekend up at Windsor Casino (Canada) and was playing a nickel "Cash Encounters" game by Bally. I have the CD that I play at work on my lunch hour so I know the concept that in the beginning you pick one of three aliens at the top of your screen and if a cow, pig or sheep come up down the row that your alien is standing up at he will swoop down and pick up the animal for extra points.

So here is what happened. I was playing 9 lines and 1 (so all the lines were covered). I do know that the extra points would be less than if you were playing 45 credits.... Well I kept having animals pop up on my line, but the alien would not pick up the animal every time (in fact, it was after every seventh animal) that it would pick up one for a mere 30 points.

I know that the casino can change the chip to the higher or lower percentages, but how can it change the actual play of the game? I'm really confused on this one. I could see if they wanted to change the odds that the animals just don't appear on that line, but to appear and not pay--- Was this a defective machine and should I have called someone over to have a technician look at it? I know it was only nickels, but they were hard-earned nickels never the less.


Dear Nancy,

If a machine does not operate the way the help screens say it should or it pays you less than the paytable specifies, it should be reported to the casino and to the local gaming commission. The only information players have about how a machine operates is in the paytable and on the help screens, so that information better be correct.

It's been a long time since I've played Cash Encounters, but I remember being confused about how the alien abduction (I think that's what they call it) bonus worked and I think my confusion had to do with why the bonus didn't occur every time an animal of the proper color appeared.

Did you check the help screens on the game? The solution to the mystery of why the bonus doesn't occur all the time is there and I bet the casino program operates a little differently than the PC program. I doubt the machine was defective.

You may have only been betting nickels, but those nickels add up. Moreover, casino gambling involves quite a bit of trust. In exchange for giving it a shot at our bankroll, we trust that the casino is giving us a fair game. More than that, the casino's license requires that it give us a fair game. Any game that isn't fair or isn't operating properly should be reported.

Best of luck in and out of the casinos,

Dear John,

I read your emails every time I get one and really enjoy them. I have one question about your claims about the RNG though.

First, I can't seem to grasp how a game with a claim of 98% payback be expressed, counting on random events.

Second, how can a computer generate random numbers? It seems to me that a computer algorithm is set according to the programming which is different then a simple flip of a coin, random event.

And finally, what's this I've read about a program that controls the RNG. I think it's acronym is MAPP? I saw it on the Las Vegas Advisor website last summer (I can't find it there at this time).

Thanks again for your emails,

Dear Mike,

I think that's three questions. Let's take them one by one.

1) A slot machine is really just an exercise in sampling with replacement. The population we're drawing from is all the possible outcomes on the reels. Some of those outcomes return money to the player; some don't. If we add up all the money the winning combinations return and divide by the number of combinations multiplied by the number of coins we're playing, we get the long-term payback of the machine.

The random thing is which outcome will appear next. Over time, each of those outcomes will appear with a frequency very close to the frequency we'd expect given the layout of the reels and the machine will pay back a percentage very close to its long-term payback.

It's the same thing as tossing a pair of dice. Even though you don't know what the next roll will be, you know that if you plotted the number of times you rolled each possible outcome, you'd have the famous craps pyramid.

2) A computer (specifically, a deterministic function) can't generate truly random numbers. That's the the RNG in a slot machine is more correctly called a Pseudo-Random Number Generator.

There are attempts to generate truly random numbers, though. If I remember correctly, IBM placed a microphone on Fifth Avenue in New York City to sample ambient noise in order to generate random numbers for one of its mainframes in the 1960s. And I think one of Intel's chipsets generates random numbers by sampling electrical noise on the bus.

3) I've never heard of MAPP.

Best of luck in and out of the casinos,

Have you been to Southeast Oklahoma, Choctaw Casinos. Here at Hugo, they are full all the time. Lots of old country folks, with pretty good pay-offs. Sure different than Vegas.


Dear Graham,

I haven't been to any casinos in Oklahoma--or even to Oklahoma, for that matter. I did visit the Choctaw casino website ( and I see that they have a fairly large operation consisting of five casinos. I'll be sure to visit one of their casinos if I'm ever in Oklahoma.

Best of luck in and out of the casinos,

I have been playing progressive slots for about 10 years now and my question is: Have the payouts of the progressives been reduced (tightened)? I usually play Wheel of Fortune and Jeopardy.

It seems to me that when one eventually gets to "spin" or play the Jeopardy portion, the payouts are usually very small (20, 25 or 30 coins) Again, have these machines really tightened up over past year or two or is it just me?


Dear Earl,

I don't know the answer to your question. It's possible that IGT has changed the programming of these machines over the years, but I don't know that for a fact.

Slot designers have to play a balancing act with bonus rounds. The bonus round has to hit frequently enough that players have a reasonable chance of seeing it. But the more frequently a bonus round occurs, the less it can pay. The designers have to find the right balance between frequency and value for each bonus in each game.

Best of luck in and out of the casinos,

Send your slot and video poker questions to John Robison, Slot Expert, at

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