Sports Odds & Market Fair Value Lab
Analyze bookmaker overround margins, strip the bookmaker vig to uncover genuine fair probabilities, and simulate football match dynamics using bivariate Poisson modeling.
Bookmaker vs. Fair True Market Comparison
Proportional & Power Law Vig Removal| Outcome | Bookmaker Odds | Implied Prob. | Fair True Odds | Fair Prob. | xG Model Prob. | Calculated EV Edge |
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Bivariate Poisson Score Probability Matrix (0 - 5 Goals)
Cell values show likelihood of exact full-time scoreDerived Secondary Derivative Markets
Calculated directly from exact bivariate goal probabilitiesOver / Under 2.5 Goals
Over / Under 1.5 Goals
Both Teams To Score (BTTS)
Draw No Bet (DNB)
Understanding Bookmaker Markets, Vig & Expected Value
In sports wagering, bookmakers (both international and regional like Betting by MWOS in Zimbabwe) build an intentional theoretical edge into market lines. This mathematical built-in tax is known as the overround or vigorish (vig).
What is bookmaker overround and how do you calculate it?
Bookmaker implied probabilities are calculated as 1 / decimal_odds. In a fair game with zero bookmaker margin, summing the probabilities of all exhaustive mutually exclusive outcomes (Home win, Draw, Away win) equals exactly 100%. In reality, bookmaker lines sum to 104%–115%. The excess above 100% represents the bookmaker's commission.
How does the Poisson distribution model football scores?
Football goal scoring is modeled reliably as independent Poisson processes where each team scores at an expected rate (λ or xG) across 90 minutes. By calculating P(k goals) = (λ^k * e^-λ) / k! for both teams, we construct an exact score matrix yielding probabilities for 1X2, Over/Under 2.5, and Both Teams to Score.
Why do betting odds change before kickoff and in-play?
Odds are never static. As discussed by bettors in sports forums, lines move continuously due to team lineup announcements (injuries, key player suspensions), weather variations, sharp syndicate betting volume, and the bookmaker balancing liability across all sides of the market.
What is Positive Expected Value (+EV) and Kelly Criterion?
A wager offers Positive Expected Value when your estimated probability of an outcome exceeds the bookmaker's implied probability (True_Prob * Decimal_Odds > 1.0). The Kelly Criterion calculates the mathematically optimal bankroll percentage to risk to maximize long-term geometric capital growth without risking ruin.