Taking Advantage of Potential Roulette Wheel Bias

Assume a random, recreational (losing) player wants to take advantage of any bias a given roulette wheel might have. They don't know that a bias exists on a particular wheel, and they are OK with playing in that situation, but if a bias does exist, they want to be a beneficiary of it. Assume they play a simple bet, such as red/black. Would the proper strategy to take advantage of any potential bias be to simply follow the last result - e.g. bet red if the previous result was red, or something more nuanced than that, such as betting the color that came up most out of the previous X spins?

If a given wheel has a bias to a given number, if that number were red, then red would indeed repeat more often than black. It seems that such a strategy in any game where a mechanical bias might develop would at least deliver the possibility of the player doing better than the theoretical loss for the game would imply. Am I way off base here?

Red/black probably wouldn't be biased.

If the bettor likes to make straight up (35:1) bets, then betting the previous number spun would suffice, but betting the number most frequent of the last X spins would be more accurate, I think.

I don't think you could do a red/black bet on a biased wheel... You would have to bet entire segments of the wheel if you discovered there was a bias that caused the ball to land in one section more than the other. But chances are, if you are able to notice a biased wheel, then so is everyone else, and it wouldn't last long.

1) As pointed out red/black won't ever be biased.
2) It takes a large sampling size to determine a wheel bias, like 7,000 - 8,000 spins.
3) After confirming a bias the strategy would be to simply play the bias =P.

One of the simplest ways to determine a bias is a wheel that's not evenly weighted, even to the slightest degree. This might result in a section of numbers coming up "slightly" more frequently than other numbers. You'll never be able to tell by looking at the board if there's a bias, so don't look at it and go "I've seen 17 three times, it must be a biased number so I'm gonna play it!" Like I said prior it takes a much larger sampling size of 1 wheel to confirm any biases... And some casinos change their wheels, or at least rotate them between tables, frequently thus if you can't tell the difference in them you'll never know if they're being switched out or not.

Lastly, just for semantics, without a confirmed bias I hope you know each and every spin of the roulette wheel is independent. Even if 15 reds came up in a row, the odds of red and black coming up on the next roll is still about a 50/50 all the same. The past doesn't effect the future, unless you have a large enough sampling size to confirm a bias =).

>"You'll never be able to tell by looking at the board if there's a bias, so don't look at it and go "I've seen 17 three times, it must be a biased number so I'm gonna play it!"

This is at the heart of my question. Given that the 17 is theoretically no worse than any other number, a player that is already playing this game anyway and looking for a number to choose, may want to choose 17, or 17's neighbors. Perhaps there is a bias toward that section of the wheel.

>"Lastly, just for semantics, without a confirmed bias I hope you know each and every spin of the roulette wheel is independent. Even if 15 reds came up in a row, the odds of red and black coming up on the next roll is still about a 50/50 all the same. The past doesn't effect the future, unless you have a large enough sampling size to confirm a bias =)."

I'm well aware of that. What I'm saying is that people playing these games are at a mathematical disadvantage anyway. Therefore, it wouldn't hurt, and may possibly help them, to embrace a strategy that takes into account the possibility of mechanical bias. If such a strategy exists, it may improve their overall results (they may lose less overall).

Quote: cwazy

This is at the heart of my question. Given that the 17 is theoretically no worse than any other number, a player that is already playing this game anyway and looking for a number to choose, may want to choose 17, or 17's neighbors. Perhaps there is a bias toward that section of the wheel.

If a person who's just playing to play see's three 17's and decides to bet 17 and it's neighbors because there "might" be a potential bias then they're just gambling all the same. This literally gives zero extra edge as there is no confirmed bias and repeat numbers in the short run are VERY COMMON. Hell, the wheel could have a bias on the other side and if you see 17 three times and start betting it you're actually hurting yourself unknowingly. In the end without a bias each spin is an independent trial, thus the past has NO EFFECT at all on the future.

Quote: cwazy

I'm well aware of that. What I'm saying is that people playing these games are at a mathematical disadvantage anyway. Therefore, it wouldn't hurt, and may possibly help them, to embrace a strategy that takes into account the possibility of mechanical bias. If such a strategy exists, it may improve their overall results (they may lose less overall).

It wouldn't hurt, NOR HELP them is the real point of the math. It's literally just gambling and thus picking numbers you see on the board does NOTHING for you either way. You're absolutely correct in saying "well, it wouldn't hurt..." but I hope you realize that holds equally true for "well, that wouldn't help..."

It absolutely can hurt. If the wheel is biased and you mis-identify the bias and bet on the wrong numbers, you're playing a game with a stronger house edge. The trick is to identify not only whether there is a bias but what it is -- and only then to bet accordingly. Seeing one number repeat three times in 20 spins isn't a valid indicator of bias.

If you can't accurately identify whether a bias exists and what it is, guessing can absolutely lead to worse results.

I was just thinking, even if you DID find a biased roulette wheel somehow, is that even going to help you? I mean, even on a European wheel, the house edge is still relatively crappy... even if you were able to spot the bias and shave a percent, even two, off the edge, there are still better bets in the casino on FAIR games.... To give the player an edge the wheel bias would have to be so ridiculous, the house would spot it right away.

Quote: TigerWu

I was just thinking, even if you DID find a biased roulette wheel somehow, is that even going to help you? I mean, even on a European wheel, the house edge is still relatively crappy... even if you were able to spot the bias and shave a percent, even two, off the edge, there are still better bets in the casino on FAIR games.... To give the player an edge the wheel bias would have to be so ridiculous, the house would spot it right away.

That simply isn't true. There are teams that have exploited biased wheels and made millions of dollars. Do a search for "billy walters roulette".

You are correct. I have seen this exact question answered before. The strategy I read was "bet the previous number." For an unbiased wheel, this is no worse than any other strategy. For a biased one, you will be weighting your bets toward numbers which hit more often.

In reality, I think the actual likelihood of a biased wheel is very close to 0, and even if a wheel were biased, it's probably barely off. I don't think this has practical value. But as an answer to the puzzle of "develop a simple roulette strategy which could take advantage of a biased wheel to potentially make the house edge better than -1/38 of money wagered," I like it.