Six mistakes come back again and again: confirmation bias, recency bias, the favourite-longshot bias, attachment to a team you follow, refusing to look at the market, and chasing — betting more after a loss to win it back. The last one is not an analysis error: the scientific literature treats it as a behavioural marker of problem gambling.
The six mistakes, in one table
None of these mistakes comes from a lack of data. They all come from the way the data is selected, weighted or ignored.
| Mistake | Why it misleads | How to correct it |
|---|---|---|
| Confirmation bias | Only the data that confirms the hunch is kept | Explicitly look for what contradicts the starting hypothesis |
| Recency bias | The last match weighs more than the five before it | Fix the observation window before looking at the results |
| Favourite-longshot bias | High odds attract more than their probability justifies | Convert the odd into a probability before judging its appeal |
| Attachment to a team | Knowing a team well gets confused with overrating it | Check whether your analysis of a team you follow differs systematically from the market |
| Ignoring the market | An isolated opinion is never tested against anything | Compare the estimate with the consensus, even without following it |
| Chasing (winning it back) | An earlier loss weighs on an independent decision | Belongs to a responsible gambling framework, not to an analytical correction |
Confirmation bias
It is the most common bias and the hardest to spot in yourself: it looks like an analysis. The hunch comes first, the data comes next, and the search naturally turns towards whatever supports the hunch.
The telltale sign: the analysis never changes the starting conclusion. A method whose conclusion has never been overturned by the data is not a method of analysis, it is a method of justification.
Concrete correction: state the opposite hypothesis and actively look for what would support it. If nothing supports it, the initial opinion comes out stronger for good reasons.
Recency bias
The last match is the most available in memory, so the heaviest in judgement — regardless of how informative it is. A heavy defeat on the latest matchday often weighs more than five solid results before it.
Concrete correction: fix the observation window (the last six fixtures, for example) before looking at the results, and stick to it. A window chosen after the fact is always chosen for what it demonstrates.
The favourite-longshot bias
High odds attract beyond what their probability justifies. A large potential payout weighs more psychologically than a low probability deserves — an effect documented on betting markets for a long time.
Concrete correction: systematically convert the odd into a probability before judging its appeal. An odd of 12.00 corresponds to around 8.3%: the figure is far less seductive than the payout on display. The full method is on implied probability.
Attachment to a team you follow
Knowing a team well gives you the feeling that you assess it better. It is often the opposite. Regular exposure supplies plenty of qualitative information, but it comes with an emotional charge that distorts the weighting.
Concrete correction: compare your own estimates with the market on that team's matches specifically. A systematic gap in the same direction is a clear signal.
Ignoring the market
Refusing to look at the odds does not protect you from a bias: it deprives you of a point of comparison. An opinion that is never tested cannot be corrected.
The market does not have to be followed to be useful. It is enough for it to serve as a counterpoint — see prediction or odds analysis.
Chasing: a mistake of a different kind
Betting more after a loss to make up for it is not an analysis error. It is a documented behavioural marker.
Since the DSM-III-R (American Psychiatric Association, 1987), chasing has been considered a characteristic trait of problem gambling and a sign of the shift from recreational play to disordered play.
The work of Nigro and co-authors, published in the Journal of Gambling Studies, adds a useful precision: gambling-related cognitive distortions predict the frequency of chasing not only directly, but also indirectly, by narrowing the person's time horizon. In other words, the more the perspective shrinks to the very short term, the more the catching-up behaviour takes hold. The authors also observe that the general severity of gambling behaviour does not, on its own, predict chasing: the people concerned form a distinct profile.
Responsible gambling — chasing is a warning sign, not a strategy. Sports betting carries a risk of financial loss. According to the Autorité nationale des jeux (the French gambling regulator), it represents "the highest individual risk of problem gambling", with a share of excessive players six times higher than for lottery games — that is, 5.9% of sports bettors. If the urge to win back a loss keeps coming back, it is not a question of method. Set a budget, use the limit-setting or self-exclusion tools available, and talk about it: GamCare answers on 0808 802 0133, free and 24/7. Learn more about responsible gambling.
What correcting your biases allows — and what it does not
Three levels never to be confused.
- What it allows you to do — make a piece of reasoning traceable, spot the places where opinion comes before data, and separate an analysis error from risky behaviour.
- What it allows you to estimate — the relative soundness of one piece of reasoning compared with another.
- What it never allows you to conclude — that an analysis stripped of its biases becomes accurate. Correcting a bias improves the reasoning, not the result of a match.
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Read the guideFrequently asked questions
What is confirmation bias in sports betting?
It is the tendency to keep only the information that confirms an initial hunch, and to discard whatever contradicts it. There is a simple sign: the analysis never changes the initial conclusion.
Why is betting more after a loss a mistake?
Because the previous loss carries no information about the next match. Increasing the stake to make up for it turns an analytical decision into an emotional reaction.
How do you correct a bias you cannot see yourself?
By writing the analysis down before you know the result, and rereading it afterwards. Reasoning noted in advance holds up badly against rebuilding after the fact, which makes the bias visible.
Chasing losses: when does it become a problem rather than an analysis error?
When the behaviour repeats and escapes control. Since the DSM-III-R (1987), chasing has been considered a characteristic behavioural marker of problem gambling, not a simple analytical slip.
Do biases disappear with experience?
No. Experience reduces certain data errors but often feeds overconfidence, which is itself a bias.
Does OddScore provide tips?
No. OddScore compares the odds of several bookmakers, removes the margin and tracks how they evolve. The platform publishes no bet selections and provides no staking advice.
Sources & methodology
This page draws on the scientific literature devoted to gambling-related cognitive distortions and to chasing behaviour, as well as on the prevention publications of the Autorité nationale des jeux. The references were checked in full text before publication.
- Describe each bias by its mechanism, not by its name.
- Separate analysis errors from behavioural markers that fall under problem gambling.
- Attach a concrete, verifiable correction to each bias.
- Quote the numerical benchmarks with the exact wording published by their source.