Roulette

[vexel77]

Hi, my friend has been using a betting system which he claims is working. He claims to be up over £500. Heres how. He uses a wheel which displays the previous 11 spins. He waits until there is a series of running black or red say more than three in a row. He then begins to back the other colour and doubles his bets until that colour hits. It guarantess him a £10 profit when the other colour eventually hits. I know for a fact that there is no betting system that can beat roulette. Can someone please explain to me how this system is flawed. He really feels like this system can beat the game but i dont have the mathematical ability to explain to him how his system is flawed. I dont want him losing a truck load of money to a game like roulette. Thanks for the help guys.

[playersare]

http://wizardofodds.com/gambling/bettingsystems.html

[Thremp]

Its a perverse martingale.

[jman220]

There are 2 flaws:

1. Past Results do not influence future outcomes. It doesn't matter if the wheel has just hit black 10 times in a row or a 100 times in a row. The odds of it hitting black the next time is still slightly less than 50 percent.

2. Doubling your bet every time you lose because you're "bound to win sometime" does not work. You are not, in fact, "bound to win sometime" and you would need an infinite bankroll and infinite time. Losses of 20 times in a row, or 30 times in a row do happen. Eventually you're going to have a catastrophic loss.

For Example: Say your base bet is $1, if you lose 20 times in a row, your 21st bet will have to be around $512,000.

[SheetWise]

Thremp -

I've always marveled the subleties between pervese incentives, moral hazards, and an attractive nuisance -- the "perverse martingale" is new to me.

Is this the unintended consequence of trying to lose?

[SamIAm]

I assumed "perverse" in "perverse martingale" could be replaced with "convoluted" or "essentially the same as a".
-Sam

[Quadstriker]

Try saying this:

Any amount multiplied by a negative expectation gives you less than your investment in return.

[Thremp]

I think I intended it as a varaition of "weird" or "distorted", but obviously I didn't take into the shades of meaning that my new colorful language would bring with it.

[SheetWise]

[ QUOTE ]
Try saying this:

Any amount multiplied by a negative expectation gives you less than your investment in return.

[/ QUOTE ]

If it occurs in your lifetime, that's true.