Description
Return the denominator factor of binary Matthews correlation.
Classifier metrics count particular outcomes on a declared population and positive-label convention. Precision, recall and accepted-only measures use different denominators. A reporting value at an empty denominator is a policy choice, while one cell, derivative or contribution does not constitute a complete performance evaluation.
Return the denominator factor of binary Matthews correlation.
When to use this tool
Use Binary Matthews Denominator Factor when checking the stated confusion-count, metric contribution or abstention-denominator convention.
How to use the tool and how it works
- Enter tp, tn, fp, fn. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read denominator. Use the output convention below.
Return the denominator factor of binary Matthews correlation. Require nonnegative whole TP/TN/FP/FN; denominator = sqrt((TP+FP)*(TP+FN)*(TN+FP)*(TN+FN)).1
Classifier metrics use different outcome supports and denominator conventions. A zero-denominator reporting policy does not supply missing observed outcomes.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| tp | Tp | Required. Safe integer. |
| tn | Tn | Required. Safe integer. |
| fp | Fp | Required. Safe integer. |
| fn | Fn | Required. Safe integer. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| denominator | Square root of the four marginal products; zero can be returned and MCC itself is not computed. | Required. Finite number. |
{
"input": {
"tp": 3,
"tn": 4,
"fp": 1,
"fn": 2
},
"output": {
"denominator": 24.49489742783178
}
}Limitations and assumptions
- Zero denominator is returned, not replaced; no correlation numerator, undefined-value policy or complete metric is computed.
- 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
Evaluate the complete confusion table, relevant class supports and abstention coverage together; use suitable uncertainty and validation methods for conclusions about predictive performance.
References
-
Calculation and input contract: classification/binary-matthews-denominator-factor — tool.io
-
Model evaluation: classification metrics — scikit-learn developers
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