Methodology

Data source

All prices and volumes come from the Betfair Exchange, a betting exchange where customers back and lay outcomes against each other. Because exchange prices are set by people risking their own money, rather than by a bookmaker adding a margin, they are a useful reference for where a market stands.

For each market Arbworld records the current price of every outcome and the volume matched on it. The first price recorded for an outcome is kept as its opening price. Volumes are shown in pounds sterling (£), the currency Betfair reports in.

Moneyway share

Moneyway shows how the money matched in a market is split between its outcomes.

Moneyway share = volume matched on the outcome ÷ volume matched on all outcomes × 100

Shares are coloured from 30% upwards; 99% or more is the deepest red. By default, markets with less than £100 matched in total are hidden, because tiny volumes produce misleading shares; the Volume filter can lower or raise that floor.

Dropping Odds

Dropping Odds compares each outcome’s current price with its opening price.

Drop % = (opening odds − current odds) ÷ opening odds × 100

A positive value means the price has shortened (the outcome is now considered more likely); a negative value means it has drifted. Drops of 7% or more are highlighted most strongly, 3–7% moderately and under 3% lightly; rises use the same bands.

Combined Score

The Combined Score brings both signals together for every outcome whose price has shortened:

Combined Score = (1 ÷ current odds − 1 ÷ opening odds) × Moneyway share × log10(max(total volume, 1) + 1)

The first part is the change in implied probability, so a move from 2.00 to 1.80 counts for more than a move from 10.0 to 9.0 of the same percentage. It is multiplied by the outcome’s Moneyway share (0–100) and by a liquidity weight that grows slowly with the total matched volume. Outcomes whose price has not shortened score 0. Each row is ranked by its strongest outcome.

Bands: under 5, 5–15, 15–35, 35–70 and 70 or more. The score is a relative ranking aid, not a probability and not an estimate of profit.

Updates

Each table shows when its market data was last updated. Open pages refresh automatically every 60 or 120 seconds (you choose), pause while the tab is hidden and refresh again when you return. Live (in-play) markets move faster than any table can follow, so treat live figures as indicative.

Limitations

• Thin markets: with little matched volume, a single bet can move the price or the shares a long way.
• Early markets: opening prices recorded days before an event are often soft, so large early drops are common and less informative.
• Context: the data does not know team news, injuries, weather or line-ups. Check them independently.
• No prediction: none of the figures is a win probability, a tip or a guarantee. Arbworld does not accept bets.

Corrections

If a figure looks wrong, please contact us with the match and market so we can check it.

Read more: What is Moneyway? · What are Dropping Odds? · What is Combined Score? · Responsible gambling