Glossary term
Glossary term
Foundations
A number between 0.0 and 1.0 representing a binary classification model's ability to separate positive classes from negative classes. The closer the AUC is to 1.0, the better the model's ability to separate classes from each other.
For example, the following illustration shows a classification model that separates positive classes (green ovals) from negative classes (purple rectangles) perfectly. This unrealistically perfect model has an AUC of 1.0:
Conversely, the following illustration shows the results for a classification model that generated random results. This model has an AUC of 0.5:
Yes, the preceding model has an AUC of 0.5, not 0.0.
Most models are somewhere between the two extremes. For instance, the following model separates positives from negatives somewhat, and therefore has an AUC somewhere between 0.5 and 1.0:
AUC ignores any value you set for classification threshold. Instead, AUC considers all possible classification thresholds.
Click the icon to learn about the relationship between AUC and ROC curves.
Click the icon for a more formal definition of AUC.
See Classification: ROC and AUC in Machine Learning Crash Course for more information.
For example, the following illustration shows a classification model that separates positive classes (green ovals) from negative classes (purple rectangles) perfectly. This unrealistically perfect model has an AUC of 1.0:
Conversely, the following illustration shows the results for a classification model that generated random results. This model has an AUC of 0.5:
Yes, the preceding model has an AUC of 0.5, not 0.0.
Created for this library
A bank reports AUC weekly for its application-fraud model and treats a drop below 0.85 as a trigger for retraining.
A digital health vendor lists AUC as the primary metric in its FDA submission because it captures rank-ordering of risk across thresholds.
A telco's churn modeling team selects the candidate model with the highest AUC on a held-out month of customer data.
Definition source: Google for Developers Machine Learning Glossary | Creative Commons Attribution 4.0 License