1. Define the measures
ACCA's ratio guidance explains why a return ratio must pair a defined profit numerator with the corresponding denominator. Applying that reporting principle to this guide:
Net settled profit = gross returns - accepted stakes - commission - settlement fees
Yield on stakes = net settled profit / total settled stake
Return on starting bankroll = net settled profit / starting bankroll
These ratios answer different questions. Label the denominator every time rather than calling all of them ROI, following the like-for-like principle in ACCA's ratio guidance.
2. Calculate a worked example
An illustrative period has:
- total settled stake: GBP 1,000;
- gross returns: GBP 1,040;
- commission and fees: GBP 10;
- starting bankroll: GBP 500.
Net settled profit = 1,040 - 1,000 - 10 = GBP 30
Yield on stakes = 30 / 1,000 = 0.03, or 3%
Return on starting bankroll = 30 / 500 = 0.06, or 6%
The two percentages are both arithmetically correct and are not interchangeable.
3. Exclude cash transfers from profit
Depositing GBP 200 increases an operator balance but does not create GBP 200 profit. Withdrawing GBP 100 reduces the displayed balance but does not create a GBP 100 betting loss. Reconcile transfers separately.
Open bets belong in exposure, not settled profit. If the period closes with unsettled positions, publish settled results and open maximum loss separately rather than assigning an estimated cash-out value.
4. Segment without selecting
Useful pre-declared segments include model version, market, league, price band, and decision cutoff. Each segment should report total stake, net result, coverage, and uncertainty. Do not search many segments and publish only the highest yield.
Average result and variability are separate. OpenStax provides expected-value and standard-deviation definitions, while NIST documents confidence limits for a mean.
5. Apply the interpretation checklist
| Check | Why it matters |
|---|---|
| Settled period fixed in advance | Prevents stopping at a favourable point |
| Accepted rather than advertised prices | Reflects execution |
| All qualifying decisions present | Prevents selection bias |
| Commission and fees included | Produces net rather than gross result |
| Stake and bankroll denominators labelled | Prevents incomparable ROI claims |
| Drawdown and open exposure reported | Shows path risk beyond the average |
Knowing an outcome can distort judgement of the original decision; outcome-bias research supports evaluating process using the information available at the time.
Test the calculator with boundary cases
Use zero-profit rows to confirm every return measure is zero. If gross returns equal settled stakes plus commission, net profit must be zero. A complete loss on GBP 100 settled stake with no return has net profit -GBP 100 and stake yield -100%; gross return is zero, not -GBP 100. A void with the stake returned has zero net profit and should be treated consistently in the turnover denominator under a declared policy.
Then test cash flows. Adding a GBP 200 deposit must leave betting profit unchanged, while a GBP 50 withdrawal must not create a loss. Preserve both pre-fee and net outputs, but make net the headline. These checks catch the most consequential spreadsheet errors before historical percentages are interpreted.
Next step
Use Yield Betting for the next part of this topic.
Continue learning
- Next guide: In-Play Bankroll Management
- Related guide: When to Increase Betting Stakes
- Definition: Yield
Assumptions and limitations
The example is illustrative and does not imply a 3% achievable yield. Tax and accounting treatment vary by jurisdiction. Historical ROI is not a forecast, and no fixed sample threshold guarantees that an observed result represents a stable edge.
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