Lesson 5 of 9

Positive EV betting

Betting prices that are wrong in your favour, and sizing them.

  1. 5.1What a bet is actually worthEvery other idea here is built on one number: the price a bet would carry if nobody took a cut.
  2. 5.2Positive EV, and why it feels like losingBetting where the price beats the market's own fair value — the slowest-looking strategy and the one that scales furthest.
  3. 5.3The expected value formula for sports betsExpected value is the chance you win times what you win, minus the chance you lose times what you lose. Positive means the price pays more than the bet is worth.
  4. 5.4How to devig odds: four methods, workedConvert every outcome's odds to implied probability, then scale them back to 100%. How you scale is the method, and on lopsided markets the choice matters.
  5. 5.5Sharp sportsbooks, and why their prices are the benchmarkA sharp book takes big bets from winning bettors and moves its line when they bet, so its price absorbs their information. That makes it the best free estimate of the true odds.
  6. 5.6The Kelly criterion for sports betting, workedKelly stakes a fraction of your bankroll equal to your edge divided by the net odds. It maximises long-run growth if your edge is exact, which it never is, so most bettors use a quarter of it or less.
  7. 5.7Variance in sports betting: how long until an edge showsAt a 3% edge on even-money bets, you are still behind about one time in six after 1,000 bets. Results take thousands of bets to prove an edge; closing line value takes far fewer.
  8. 5.8Closing line value: the only honest scoreboardWhether the price you took beat where the market ended up — and why it predicts profit better than profit does.
  9. 5.9Positive EV betting mistakes, and how to fix themMost +EV bets that lose money long term were never +EV: the fair price was stale, still had vig in it, or came from a market too thin to trust. The rest are sizing and discipline.