+EV

[IamLeach]

Can someone direct me to an explanation of +EV?

[Weatherhead03]

I'm sure someone can expand on this but basically it stands for Expected value, as in +EV means you have an expected value of winning something whether it be 1 cent or 1 million dollars.

[transient]

It's basically a stats concept that you can use to figure out if you will make money in the long run. Here's a simple example I just made up:

You flip a coin. If it comes up heads, you win $2. If it's tails, you lose $1. The expected value is (0.5)(2) - (0.5)(1), which comes out to be 0.5. You make an average of 50 cents per game.

[AaronBrown]

Expected value is a technical term in probability. It has nothing to do with what you expect. It just means to consider all possible outcomes and add up the probability times the amount of money you get. If that's a positive number, you have a positive expected value, or +EV.

If you bet $1 on red in double-zero roulette, you have 18/38 chance of winning $1 and 20/38 of losing $1. Multiply them and add, you get +$1*18/38 - $1*20/38 = -2/38, so -EV. If the house paid 2 to 1, you would get $2 for winning and your expected value would be +$2*18/38 - $1*20/38 = +16/38.

A very important result is that the EV of a series of bets is equal to the sum of the EV's. It doesn't matter whether the bets are dependent, or if the size varies. So no betting scheme can turn negative EV bets into a positive EV outcome.