The difference between the odds you took and the odds the bookmaker closed at — the most reliable indicator of long-term betting skill.
Closing Line Value (CLV) measures whether the odds you backed were better than the odds the bookmaker closed at just before kick-off. If you backed a team at 2.50 and the market closed at 2.00, you beat the closing line — implying your selection was made before the market priced in information that shortened the team.
Because bookmakers sharpen their prices as more money and information enters the market, the closing price is considered the most efficient estimate of true probability. Consistently beating the closing line is the strongest evidence that a bettor has genuine edge — better even than ROI over short samples.
A bettor with +8% CLV over 200 bets is almost certainly skilled, even if variance has produced a temporarily negative ROI. A bettor with -3% CLV but positive ROI has almost certainly been running lucky — their results will regress. CLV removes variance from the skill assessment.
CLV = (1 ÷ closing odds) − (1 ÷ odds taken). A positive value means you beat the closing line. Track this alongside ROI to distinguish skill from luck in your betting record.
Expected Value (EV)
The average outcome of a bet over a large number of repetitions — positive EV means the bet profits long-term; negative EV means it loses.
Value Bet
A bet where the odds offered by the bookmaker are higher than the true probability of the outcome, giving you a positive expected value over the long run.
Implied Probability
The probability of an outcome embedded in bookmaker odds — calculated by dividing 1 by the decimal odds.
For informational and educational purposes only. Disclaimer
