Measure to compare true observed labels with predicted labels in binary classification tasks.
Arguments
- truth
(
factor()
)
True (observed) labels. Must have the exactly same two levels and the same length asresponse
.- response
(
factor()
)
Predicted response labels. Must have the exactly same two levels and the same length astruth
.- positive
(
character(1))
Name of the positive class.- ...
(
any
)
Additional arguments. Currently ignored.
Details
The Matthews Correlation Coefficient is defined as $$ \frac{\mathrm{TP} \cdot \mathrm{TN} - \mathrm{FP} \cdot \mathrm{FN}}{\sqrt{(\mathrm{TP} + \mathrm{FP}) (\mathrm{TP} + \mathrm{FN}) (\mathrm{TN} + \mathrm{FP}) (\mathrm{TN} + \mathrm{FN})}}. $$
This above formula is undefined if any of the four sums in the denominator is 0. The denominator is then set to 1.
References
Matthews BW (1975). “Comparison of the predicted and observed secondary structure of T4 phage lysozyme.” Biochimica et Biophysica Acta (BBA) - Protein Structure, 405(2), 442--451. doi:10.1016/0005-2795(75)90109-9 .