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Brier Reference Class Contribution

Compare one explicit class Brier contribution with a supplied reference probability under the same binary observation.

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Description

Compare predicted and reference single-class squared probability errors.

Prediction metrics depend on the observation definition, reference forecast, denominator sign and aggregation. A single error contribution differs from a mean score or normalized skill measure. Interval midpoints, squared probability errors and seasonal-denominator labels must retain the exact convention before models are compared.

Compare predicted and reference single-class squared probability errors.

When to use this tool

Use Brier Reference Class Contribution when you already have classProbability, observedClass, referenceProbability and need to compare predicted and reference single-class squared probability errors.

How to use the tool and how it works

  1. Enter classProbability, observedClass, referenceProbability. Use the units and conventions below.
  2. Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
  3. Read classSquaredError, referenceSquaredError, improvement. Use the output convention below.

Require both probabilities in [0,1]; observation is 1 when observedClass else 0. Return each (probability-observation)² and reference error minus class error as improvement.1

Input fieldMeaning and unitsAccepted input
classProbabilityClass ProbabilityRequired. Finite number; minimum 0; maximum 1.
observedClassObserved ClassRequired. Boolean.
referenceProbabilityReference ProbabilityRequired. Finite number; minimum 0; maximum 1.
Output fieldInterpretationReturned shape
classSquaredErrorOne (classProbability-observedClass)^2 contribution; not an aggregated multiclass Brier score.Required. Finite number.
referenceSquaredErrorReference Squared ErrorRequired. Finite number.
improvementReference contribution-current contribution; positive favors the current probability for this one outcome.Required. Finite number.
json
{
  "input": {
    "classProbability": 0.5,
    "observedClass": true,
    "referenceProbability": 0.25
  },
  "output": {
    "classSquaredError": 0.25,
    "referenceSquaredError": 0.5625,
    "improvement": 0.3125
  }
}

Limitations and assumptions

  • Positive improvement means smaller error than the supplied reference for this observation; this is neither an aggregate multicategory score nor a normalized skill ratio.
  • 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

Calculate the complete documented metric over the intended observations and reference baseline. Review missing/zero actuals, aggregation weights and outcome coding; one contribution or source label does not establish overall forecasting quality.

References

  1. Calculation and input contract: metrics/brier-reference-class-contribution — tool.io

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