Expected Value (EV)

Every bet we make is really a bet on a number we can't see: its expected value. Get that number positive often enough and the results take care of themselves.

EV is what you'd win or lose per bet on average if you could repeat it endlessly. If you reckon something is genuinely 50% to happen and you can back it at 2.10, that's positive EV: you're getting paid more than the true odds. Back the same thing at 1.80 and you're lighting money on fire, even when it wins.

The hard part isn't the formula, it's honestly estimating the true probability. That's where research, models and discipline live. Closing line value is basically EV's receipt: keep beating the close and your EV estimates were probably real.