Keep the outcome amounts and the cost convention together
Suppose a fictional closed-outcome model pays a gross +300 USD on a win or −100 USD on a loss. A charge described only as 10 USD is incomplete: it might apply to the whole round trip, to each leg or only to a particular outcome in an invented contract.
State the convention before calculation. A per-leg charge applied to two entered legs is not the same total as one round-trip charge. The examples below are teaching assumptions, not actual broker tariffs or an assertion that any provider uses winner-only charges.
Recompute the supplied net win and net loss
Under a 10 USD round-trip cost on every outcome, the net winning amount is 290 and the net losing magnitude is 110. The zero-mean proportion for this two-outcome model is 110/(290+110), or 27.5%. With 10 USD on each of two legs, the corresponding amounts are 280 and 120, giving 30%.
For a separate invented winner-only charge of 10 USD, the amounts are 290 and 100. The same algebra gives 100/390, about 25.641%. Changing the fee convention changes the model; it does not improve a real trading record.
| Fictional cost convention | Net win / loss magnitude | Zero-mean proportion |
|---|---|---|
| 10 USD round trip on both outcomes | 290 / 110 | 27.5% |
| 10 USD per leg, two legs | 280 / 120 | 30% |
| 10 USD only on winning outcome | 290 / 100 | About 25.641% |
A required proportion is not an estimated probability
The break-even proportion answers a conditional algebra question for fixed supplied payoffs. It does not tell you how often a strategy will win. A realised mean instead depends on actual observations, their count and the inclusion rules; the NIST definition of a mean does not establish a trading probability.
Variable outcomes, rebates, additional fees, partial fills or unresolved positions can require a different model. Do not force those records into a fixed +300/−100 example merely because the formula returns a precise percentage. Missing inputs can leave the relevant statistic unknown.
An amount, a percentage and a basis-point charge are different inputs
The ten-dollar examples use fixed amounts in USD. A fee entered as a percentage needs its own stated base, and a basis-point value needs conversion to a decimal rate before multiplication. Do not type 10 into a rate field merely because the source says 10 USD. Similarly, a charge already included in a supplied net payoff must not be deducted again. Retaining the input’s original unit can prevent an apparent disagreement between two otherwise correct calculators.
Keep an input note beside the calculator output
Record USD units, gross payoff assumptions, which outcomes incur a charge, how many legs are counted and whether a fee is already included in an entered amount. This helps prevent double deduction and gives another reviewer enough information to reproduce the result.
This companion case does not recommend a payoff target, position size or strategy. It calculates no authenticated result for the linked offer. All charges and outcome values are fictional, and the separate main page remains available through the optional link below.
The optional link below leads to this site's separate crypto signals and Telegram updates offer. The record method is usable without that offer. It does not independently verify the offer, establish country eligibility or turn the teaching example into an actual transaction.
Primary sources and scope
- NIST/SEMATECH: Measures of Location
Arithmetic mean uses the sum divided by the count of observations. The worked cases here are invented, not evidence of performance. Checked 2026-10-21.