Definition
Positive EV (+EV) describes a bet where the price offered is better than the true probability of the outcome. If you estimate a team's true win probability at 55% but the implied probability in the market is 50%, you have a +EV bet. Finding +EV requires an accurate probability model and lines that haven't already priced in your edge. +EV betting does not guarantee wins on individual bets — it guarantees profits over a large enough sample, assuming your probability estimates are correct.
Worked Example
Market: Team B +130 (implied probability 43.5%). Your model: Team B wins 50% of the time. EV per $100 bet = (0.50 × $130) − (0.50 × $100) = $65 − $50 = +$15. Edge = 50% − 43.5% = 6.5%. Over 200 bets at $100: expected profit = 200 × $15 = $3,000, before variance narrows results toward that expectation.
Why It Matters
+EV is the entire goal. A bettor placing only +EV bets will profit long-run by mathematical certainty; a bettor chasing streaks and gut feelings without +EV will lose by the same certainty.