Description
Divide factor × abs(predicted - actual) by abs(actual) + abs(predicted).
Percentage-style errors depend on their denominator, scaling factor, and zero policy. A fractional symmetric error and a signed percent error have different ranges and interpretations.
Divide factor × abs(predicted - actual) by abs(actual) + abs(predicted).
When to use this tool
Use Symmetric Mape Denominator Convention when you need one explicit relative-error convention.
How to use the tool and how it works
- Enter actual, predicted, factor. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read error, undefinedPair. Inspect undefinedPair before interpreting the associated values.
Divide factor × abs(predicted - actual) by abs(actual) + abs(predicted). At a zero denominator return error zero and undefinedPair true.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| actual | Observed value on the same scale and unit as its prediction. | Required. Finite number. |
| predicted | Predicted value on the same scale and unit as actual. | Required. Finite number. |
| factor | Factor | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| error | Error | Required. Finite number. |
| undefinedPair | Undefined Pair | Required. Boolean. |
{
"input": {
"actual": 2,
"predicted": 6,
"factor": 2
},
"output": {
"error": 1,
"undefinedPair": false
}
}Limitations and assumptions
- Factor defines the reporting convention; zero for an undefined pair is a placeholder and not an observed percentage error.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Report the denominator and zero policy with aggregates, and compare absolute errors when relative denominators are unstable.
References
Similar or alternative tools
- Metrics: Smape Single Pair Zero Policy
Use 2 × abs(forecast - actual) / (abs(actual) + abs(forecast)) for smapeFraction.
- Metrics: Percentage Error Zero Actual Label
When actual is nonzero, return 100 × (forecast - actual) / abs(actual).