Peer-reviewed theoryEvidence: StrongAdvanced3 min summary
John L. Kelly Jr. · 1956 · Bell System Technical Journal
Maximising the expected logarithm of wealth gives the fastest long-run exponential growth; with fair odds that maximum growth rate equals the channel's information rate. The staking rule derived here became known as the Kelly criterion.
Does not show: That full Kelly stakes are sensible when probabilities are estimated, or that any real betting edge exists.
Used in: Kelly, Drawdowns and the Danger of a Confident Forecast · Lesson 4 · Lesson 13 · +1 more
Peer-reviewed empiricalEvidence: ModerateAdvanced4 min summary
Mark J. Dixon, Stuart G. Coles · 1997 · Journal of the Royal Statistical Society: Series C (Applied Statistics)
The model describes score outcomes well, and the authors report a positive return when its probabilities were used to select bets against bookmaker odds in their historical evaluation.
Does not show: That a Dixon–Coles model beats today's football markets after margins, limits and competition.
Used in: Lesson 1 · Lesson 8 · Lesson 10 · +2 more
Literature reviewEvidence: StrongIntermediate3 min summary
Raymond D. Sauer · 1998 · Journal of Economic Literature
To a first approximation, wagering prices are efficient forecasts of outcomes and absorb information as lines move, while documented exceptions such as the favourite–longshot bias remain important.
Does not show: That every market or price is efficient, or that the anomalies it lists can be exploited today.
Used in: The Edge Is in the Price, Not in Picking the Winner · Lesson 2 · Lesson 4 · +3 more
Peer-reviewed empiricalEvidence: ModerateIntermediate3 min summary
Erik Štrumbelj · 2014 · International Journal of Forecasting
Probabilities from Shin's model were more accurate than basic normalisation or regression in the samples studied; bookmakers differed as sources of probability, and exchange prices were not always the best source, especially in smaller markets.
Does not show: That any de-vig method recovers the true probability, or that de-vigged prices reveal profitable bets.
Used in: The Edge Is in the Price, Not in Picking the Winner · Lesson 3 · Lesson 7 · +3 more
Peer-reviewed theoryEvidence: ModerateAdvanced3 min summary
Rose D. Baker, Ian G. McHale · 2013 · Decision Analysis
When probabilities are estimated with error, Kelly stakes should be shrunk; shrunken strategies outperformed raw Kelly out of sample in their simulations and tennis illustration.
Does not show: A universal fraction of Kelly that is safe for everyone, or that the underlying tennis model had a real edge.
Used in: Kelly, Drawdowns and the Danger of a Confident Forecast · Lesson 4 · Lesson 14 · +1 more
Peer-reviewed theoryEvidence: ModerateExpert3 min summary
Enzo Busseti, Ernest K. Ryu, Stephen Boyd · 2016 · The Journal of Investing
In simulations, risk-constrained Kelly bets achieved better trade-offs than fractional Kelly: more growth at the same drawdown risk, or less drawdown risk at the same growth.
Does not show: That drawdown constraints protect a bettor whose probability estimates are wrong.
Used in: Kelly, Drawdowns and the Danger of a Confident Forecast · Lesson 15
PreprintEvidence: LimitedIntermediate3 min summary
Lisandro Kaunitz, Shenjun Zhong, Javier Kreiner · 2017 · arXiv preprint
The authors report that the strategy was profitable in a historical simulation, in a simulation on more granular odds data and in a short real-money trial, and that bookmakers restricted their accounts during the trial.
Does not show: That cross-bookmaker discrepancies remain available or executable at meaningful stakes today.
Used in: The Edge Is in the Price, Not in Picking the Winner · A Profitable Backtest That Never Existed · Lesson 6 · +3 more
Peer-reviewed theoryEvidence: ModerateAdvanced3 min summary
Karl Whelan · 2024 · Economica
Bettor disagreement combined with bookmaker risk aversion can generate a favourite–longshot pattern (worse returns on long shots) without assuming that bettors love risk.
Does not show: That backing favourites is profitable, or how large the bias is in any particular market today.
Used in: Lesson 11 · Lesson 22
Peer-reviewed empiricalEvidence: StrongAdvanced4 min summary
David Winkelmann, Marius Ötting, Christian Deutscher, Tomasz Makarewicz · 2024 · Journal of Sports Economics
Apparent inefficiencies appear in individual seasons but do not persist systematically across seasons or leagues, and simulations show that significant single-season results are likely even in a fully efficient market.
Does not show: That no bettor can ever find an edge; it shows that single-season evidence is weak.
Used in: The Edge Is in the Price, Not in Picking the Winner · A Profitable Backtest That Never Existed · Lesson 5 · +5 more
Peer-reviewed replicationEvidence: StrongIntermediate4 min summary
Lawrence Clegg, John Cartlidge · 2025 · International Journal of Forecasting
Much of the original out-of-sample profit depended on a single outlier bet recorded at erroneously long odds; after correction only one strategy remained significantly profitable in the original period, returns came mainly from individual bookmakers' mispricing rather than the buzz signal, and there were no further profits in data after 2020.
Does not show: That attention-based signals never contain information; it shows this published profit was not robust.
Used in: A Profitable Backtest That Never Existed · Lesson 5 · Lesson 6 · +4 more
Peer-reviewed empiricalEvidence: ModerateAdvanced3 min summary
Jay Simon · 2024 · Management Science
Sportsbook forecasts were mostly reliable, yet line changes were negatively autocorrelated (overreaction), forecast quality did not always improve toward game time, and simple strategies would have earned significant hypothetical profits.
Does not show: That football markets behave the same way, or that the hypothetical strategies were executable at scale.
Used in: The Edge Is in the Price, Not in Picking the Winner · Lesson 6 · Lesson 9 · +2 more
Peer-reviewed empiricalEvidence: LimitedIntermediate4 min summary
Conor Walsh, Alok Joshi · 2024 · Machine Learning with Applications
Selecting models by calibration produced better simulated betting outcomes than selecting by accuracy. After the 2025 corrigendum, average returns were negative for both selection rules (about −9.8% for calibration versus −26.8% for accuracy), while the best single models reached about +23.1% and +10.9%.
Does not show: That calibrated models are profitable; the corrected average returns were negative.
Correction: Corrigendum, Machine Learning with Applications 19 (2025), 100627 (doi:10.1016/j.mlwa.2025.100627). The original 2024 return figures were withdrawn; use the corrected values.
Used in: Kelly, Drawdowns and the Danger of a Confident Forecast · Lesson 18 · Lesson 23 · +1 more
Peer-reviewed empiricalEvidence: ModerateAdvanced3 min summary
Tadgh Hegarty, Karl Whelan · 2026 · Oxford Economic Papers
Bookmakers facing less competition set prices with a favourite–longshot bias, while the competitive market shows little of it; the model's prediction about returns on draws is also supported. Working-paper versions describe a sample of tens of thousands of matches (later drafts cite over 150,000).
Does not show: That a favourite strategy beats competitive markets; the bias is concentrated where competition is weaker.
Used in: The Edge Is in the Price, Not in Picking the Winner · Lesson 11 · Lesson 22
Peer-reviewed methodsEvidence: ModerateExpert3 min summary
Tadgh Hegarty, Karl Whelan · 2024 · Sports Economics Review
Tests based on normalised probabilities behave well; tests based on raw inverse odds do not, and are biased against finding a favourite–longshot bias.
Does not show: Any profitable strategy; it shows how test design can change conclusions.
Used in: A Profitable Backtest That Never Existed · Lesson 2 · Lesson 11 · +1 more
Peer-reviewed theoryEvidence: ModerateExpert2 min summary
Hyun Song Shin · 1992 · The Economic Journal
A bookmaker protecting against insiders sets odds that produce a favourite–longshot bias; the model underlies the Shin de-vig method.
Does not show: How much insider trading exists in a given market.
Used in: The Edge Is in the Price, Not in Picking the Winner · Lesson 3
Peer-reviewed empiricalEvidence: ModerateExpert2 min summary
Hyun Song Shin · 1993 · The Economic Journal
Provides the estimation approach later used to convert odds into probabilities under Shin's model.
Does not show: That Shin probabilities are always the most accurate.
Used in: Lesson 3
Peer-reviewed empiricalEvidence: LimitedIntermediate2 min summary
Stephen R. Clarke, Stephanie Kovalchik, Martin Ingram · 2017 · American Journal of Sports Science
The power method outperformed normalisation on all three datasets and was comparable to or better than Shin, while always producing valid probabilities.
Does not show: That one method is best for every football market.
Used in: The Edge Is in the Price, Not in Picking the Winner · Lesson 3
Peer-reviewed empiricalEvidence: ModerateAdvanced2 min summary
M. J. Maher · 1982 · Statistica Neerlandica
Team-strength Poisson models fit football scores reasonably well; allowing modest dependence between the two scores improves the fit.
Does not show: Anything about betting profitability.
Used in: Lesson 1 · Lesson 5 · Lesson 8 · +3 more
Peer-reviewed methodsEvidence: StrongIntermediate2 min summary
Glenn W. Brier · 1950 · Monthly Weather Review
Introduces what is now called the Brier score, which rewards forecasts that are both well calibrated and sharp.
Does not show: Whether a forecast can make money against a market.
Used in: Lesson 18 · Lesson 23
Peer-reviewed theoryEvidence: StrongExpert2 min summary
Tilmann Gneiting, Adrian E. Raftery · 2007 · Journal of the American Statistical Association
Explains why strictly proper scores such as the Brier and logarithmic scores reward honest probability forecasts.
Does not show: That a better-scored forecast will be profitable against a market.
Used in: Lesson 18 · Lesson 23
Book chapterEvidence: ModerateAdvanced2 min summary
Edward O. Thorp · 2006 · Handbook of Asset and Liability Management, Vol. 1 (Elsevier)
Explains Kelly's growth properties and why many practitioners bet a fraction of Kelly to reduce volatility.
Does not show: That any particular sports-betting edge exists.
Used in: Kelly, Drawdowns and the Danger of a Confident Forecast · Lesson 13
Peer-reviewed theoryEvidence: ModerateAdvanced2 min summary
Leonard C. MacLean, Edward O. Thorp, William T. Ziemba · 2010 · Quantitative Finance
Kelly maximises long-run growth but can be very risky in the short run; fractional Kelly trades some growth for substantially lower risk.
Does not show: Which fraction suits an individual bettor.
Used in: Kelly, Drawdowns and the Danger of a Confident Forecast · Lesson 13 · Lesson 14 · +1 more
Peer-reviewed theoryEvidence: StrongAdvanced3 min summary
David H. Bailey, Jonathan M. Borwein, Marcos López de Prado, Qiji Jim Zhu · 2014 · Notices of the American Mathematical Society
With enough trials, an impressive in-sample backtest is likely even when no strategy has skill, and overfit strategies tend to perform worse out of sample.
Does not show: That every strong backtest is overfit; it shows why the number of trials must be reported.
Used in: A Profitable Backtest That Never Existed · Lesson 12 · Lesson 19 · +3 more
Peer-reviewed empiricalEvidence: LimitedIntermediate2 min summary
Philip Ramirez, J. James Reade, Carl Singleton · 2023 · International Journal of Forecasting
Reported that attention-related signals were associated with mispricing and profitable strategies; later corrected by Clegg & Cartlidge.
Does not show: A durable profitable strategy, once the outlier bet is corrected.
Used in: A Profitable Backtest That Never Existed · Lesson 21