Conditional Probability

"Conditional probability is the probability of some event A, given the occurrence of some other event B."

How does this apply to the game of roulette?

Quote: EvenBob

"Conditional probability is the probability of some event A, given the occurrence of some other event B."

How does this apply to the game of roulette?

I suppose you could ask a problem like this:

What is the probability that last number was 23, given that it was red? The general formula for the answer would be pr(red and 23)/pr(red) = (1/38)/(18/38) = 1/18.

Quote: Wizard

I suppose you could ask a problem like this:

Empirical probability estimates probabilities from experience and observation. Empirical means: 'Relying on experience or observation alone without due regard for system and theory.' Empirical Probability of an event is an estimate that the event will happen based on collecting data. It is based specifically on direct observations. I'm wondering if this and conditional probability can be applied to roulette in picking the next outcome for the even chances.

Past spins have absolutely no impact on future spins. How would you use the experience and observation to aid you?

Quote: EvenBob

Empirical probability estimates probabilities from experience and observation. Empirical means: 'Relying on experience or observation alone without due regard for system and theory.' Empirical Probability of an event is an estimate that the event will happen based on collecting data. It is based specifically on direct observations. I'm wondering if this and conditional probability can be applied to roulette in picking the next outcome for the even chances.

You would need to generate a hypothesis before going out and collecting your data, and the sample size large enough to prove your hypothesis is so large that it wouldn't be worth your time. Moreover, unless your hypothesis is that the wheel is sufficiently random, it's likely to be disproven anyway.

Quote: SolidAU

You would need to generate a hypothesis before going out and collecting your data, and the sample size large enough to prove your hypothesis is so large that it wouldn't be worth your time. Moreover, unless your hypothesis is that the wheel is sufficiently random, it's likely to be disproven anyway.

"Empirical probability estimates probabilities from experience and observation. Empirical means: 'Relying on experience or observation alone without due regard for system and theory."

My Vegas friend claims to win at roulette using experience and observation, I'm trying to figure out how he does it. Intuitive Probability is used as well.

Intuitive Probability? Um... no.

Quote: dwheatley

Intuitive Probability? Um... no.

Intuitive Probability is a legitimate branch of probability science, books have been written about it.

Empirical probability is for when you know something will happen, but you don't know how often it will occur. If I stand on the same intersection every day for 6 months and count the number of cars that run a red light, I can use empirical probability to estimate the likelihood that the next car will run a red light.

But, in Roulette, you know EXACTLY what the odds of the ball landing on a particular number are (1/38). And it has NOTHING to do with what past balls have done.

Have you ever read any of those books about intuitive probability? Here are some questions that are in mine (M. Gardner, The Colossal Book of Short Puzzles and Problems, W. W. Norton & Company, 2006)

Which situation is more likely after four bridge hands have been dealt: you and your partner hold all the clubs or you and your partner have no clubs? (A game of bridge is played by two pairs of players, with players on a team sitting opposite each other) [Gardner, p. 39].


A secretary types four letters to four people and addresses the four envelopes. If she inserts the letters at random, each in a different envelope, what is the probability that exactly three letters will go into the right envelope? [Gardner, p. 39].


A pencil with pentagonal cross-section has a maker's logo imprinted on one of its five faces. If the pencil is rolled on the table, what is probability that it stops with the logo facing up? [Winkler, p. 1].

(saved on typing and used the examples available at http://www.cut-the-knot.org/Probability/IntuitiveProbability.shtml#Gardner)

I highly recommend the book. It's fun, and presents a variable degree of difficulty. I used my copy for in-flight amusement for about 6 months before I exhausted the interesting problems.

Intuitive probability is the logical sense that keeps a person from falling for a trick question. That doesn't really apply to Roulette in any way that I can see.

You never did answer the question about your friend's betting amount. Does he just increase his bet when he loses? That is a very simple way to ensure that the majority of sessions are winning ones (with some big losing sessions).


*EDIT* I just noticed that the 3rd example from the website was from a different book. Here is the full cite for that question: P. Winkler, Mathematical Mind-Benders, A K Peters, 2007

He never increases his bet, its always the same.

wtf ru talking about? he asked for an example of conditional probability and was given one.

Quote: rudeboyoi

wtf ru talking about?

apparently, empircal research and intuitive probability

Quote: rudeboyoi

he asked for an example of conditional probability and was given one.

yes, and then he said

Quote: EvenBob

"Empirical probability estimates probabilities from experience and observation. Empirical means: 'Relying on experience or observation alone without due regard for system and theory."

My Vegas friend claims to win at roulette using experience and observation, I'm trying to figure out how he does it. Intuitive Probability is used as well.

To the extent that he defined empirical and then still missed the point about the lack of applicability to this situation, explanation was clearly necessary.

Quote: rdw4potus

and then still missed the point .

Not true. The field of probability theory is a broad one and I'm not sure every avenue has been explored.

What a bunch of nonsense.

Quote: EvenBob

Not true. The field of probability theory is a broad one and I'm not sure every avenue has been explored.

Maybe you're right. And I know just the person to help you...Tuttigym!

Intuitive probability is a vague term referring to our ability to resolve difficult probability questions intuitively. Some people may not understand Bayesian probability, but can still answer questions that might otherwise require it, using 'intuitive probability'.

It CANNOT be used to predict roulette outcomes.

Quote: dwheatley

Intuitive probability is a vague term referring to our ability to resolve difficult probability questions intuitively. Some people may not understand Bayesian probability, but can still answer questions that might otherwise require it, using 'intuitive probability'.

It CANNOT be used to predict roulette outcomes.

Why are you so certain?

Quote: EvenBob

Quote: dwheatley

...It CANNOT be used to predict roulette outcomes.

Why are you so certain?

I rather disagree. I think it probably can indeed be used to predict roulette outcomes. I just think those predictions would be absolutely worthless.

Quote: EvenBob

Why are you so certain?

Because it's extremely basic math. Each spin is completely random. On each spin, each space is equally likely to win. No past spins, which are what you'd use with your intuitive/empitical/conditional probability, have any effect at all on future spins.

The wizard addresses similar issues here and here.

Quote: rdw4potus

No past spins, which are what you'd use with your intuitive/empitical/conditional probability, have any effect at all on future spins.

]

Of course they can't physically effect the next spin, how could they. So by using Intuitive Probability, its not possible to 'think randomly' and make semi accurate bets on the even chances? I think some people have mastered it, just not very many.

Quote: Doc

I rather disagree. I think it probably can indeed be used to predict roulette outcomes. I just think those predictions would be absolutely worthless.

Do you think they would do better or worse than just guessing blindly? Is it possible to lose badly on purpose on the even chances?

Quote: EvenBob

Of course they can't physically effect the next spin, how could they. So by using Intuitive Probability, its not possible to 'think randomly' and make semi accurate bets on the even chances? I think some people have mastered it, just not very many.

Maybe we should merge this thread with the astrology thread. I think that it may be possible to use intuitive probability to accurately predict the next roll. But I think it depends on the exact moon phase and the relative gravitational effects of various celestial bodies. The formula you'd need to know would be different at different times of the year. Maybe that's why it takes so long to master your friend's method?

Quote: rdw4potus

Maybe we should merge this thread with the astrology thread.

Naw. Is there a Nostradomas thread? Seriously, do you think its possible to lose on purpose in roulette, to make more bad bets on the even chances than you would by just guessing randomly?

Quote: EvenBob

Do you think they would do better or worse than just guessing blindly? Is it possible to lose badly on purpose on the even chances?

(1) No.

(2) Yes, by over-betting your bankroll or by playing too long. Or you could bet both red/black, both odd/even, etc. until the green numbers took your money.

No. The wheel is random and doesn't know what you're picking. It's just as likely to land on any number, you can't outsmart it in order to win or lose.

Quote: rdw4potus

No. The wheel is random and doesn't know what you're picking. It's just as likely to land on any number, you can't outsmart it in order to win or lose.

Why isn't it possible to think randomly and mimic what the wheel is doing? Seems to me experience would give you that advantage.

Quote: EvenBob

Why isn't it possible to think randomly and mimic what the wheel is doing? Seems to me experience would give you that advantage.

How is that an advantage? The wheel is random. Mimicking a random act neither increases nor decreases the probability that you'll succeed in matching the wheel. Whether you always bet red or you move your bet randomly between red and black, you'll still match the spin 18/38ths of the time over the long run.

It's not possible to "mimic what the wheel is doing." The wheel is acting randomly, and is therefore unpredictible by definition.

Quote: rdw4potus

It's not possible to "mimic what the wheel is doing."

I'm not convinced the random the wheel is producing is quite the uncrackable code you think it is. There are a few people who seem to have figured it out, but not many. I suppose its probably more work than I realize.

Quote: EvenBob

Why isn't it possible to think randomly and mimic what the wheel is doing? Seems to me experience would give you that advantage.

http://en.wikipedia.org/wiki/Random

Once you understand the concept of randomness, you'll understand how that question doesn't make any sense.

Also, here's a perfect quote from that page:

Quote:

One of the intriguing aspects of random processes is that it is hard to know whether a process is truly random. An observer may suspect that there is some "key" that unlocks the message. This is one of the foundations of superstition, and is also a motivation for discovery in science and mathematics.

Finally, note the picture of the casino game in the article.

Quote: bluefire

http://en.wikipedia.org/wiki/Random

Once you understand the concept of randomness, you'll understand how that question doesn't make any sense.

I've seen it done, somethings going on.

what you are saying is like flipping a coin and flipping another coin to decide which side you will call on the other coin.

Sigh...

Quote: EvenBob

Quote: bluefire

http://en.wikipedia.org/wiki/Random

Once you understand the concept of randomness, you'll understand how that question doesn't make any sense.

I've seen it done, somethings going on.

You ignored the quote about a key

Quote: EvenBob

"Conditional probability is the probability of some event A, given the occurrence of some other event B."

How does this apply to the game of roulette?

Study "Klotz strategy/criteria", is a bayesian way to see roulette.

Quote: EvenBob

Why isn't it possible to think randomly and mimic what the wheel is doing? Seems to me experience would give you that advantage.

In my opinion, our brain is not capable to create random.

We unconciesly make patterns.

In case we guess results we must have s strong criterion to beat the house.

We cannot win or lose higher or lower than true probability with +/- 3.5 standard deviations.

Bayesian probability often is closer to classical probability and takes less trials to find an answer.