We’re back with another question/comment following my discussion about how a slot machine’s payback works in this reel we posted to our Flip The Switch page on Facebook and Instagram:
I wish you could explain better how the RTP is calculated over the long term. We know casinos set their machines to hold a certain percentage.
Eric H.
I love to use an analogy of a bag of marbles. For simplicity, let’s say there’s 100 marbles in there. 95 are green and 5 are red. Each drawing of a marble is like a spin of a slot. Each time you grab one, most importantly, the marble goes back in the bag, so whenever you grab one there’s always that same 100 we started with.
That means on any “spin” where you grab a marble, you have a 95% chance of grabbing a green marble and 5% chance of grabbing a red one. Sure, you might grab a green one 100 times in a row, or a red one 5 times in a row, but over the long term, your chances of grabbing a green one are 95% at any given time.
And, the more marbles you grab, the more likely your average will converge on that 95% expectation, even when occasional variance will occur from the norm.
With slots the idea is similar, but the number of combinations might be millions. So let’s use a different example. Let’s say the slot has 1 million unique combinations. Each spin costs $1. Each outcome has an equal chance of coming out. If you were to buy every combination once, that would cost you $1 million.
Now let’s say the total amount you’d win by getting all those combinations once was $950,000. $950,000 out of $1 million is 95% – effectively it’s the same idea as the marbles. Your chances of any combination being the same, over the long run you’d expect each combination to come out roughly the same number of times, and that’s how the payback is achieved long term.
Are there massive wins included in there? Sure – and for those players that get them, their performance for that slot session will likely be a lot better than 95%. And there are plenty of losing spins or “false win” spins that pay less than your bet back, and players that see mostly those will fall under.
But this is why I say the lifetime of a machine matters – the longer a machine is on the casino floor, the more spins will be taken, and the more likely those ups and downs will average out and converge on that long term RTP.
I hope this helps you and others, Eric, better understand how it all works!
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