What does a low AUC-ROC value indicate about a model?

A low AUC-ROC value indicates that the model struggles to distinguish between positive and negative classes effectively. The AUC-ROC (Area Under the Curve - Receiver Operating Characteristic) score is a measure of a model's ability to differentiate between classes, with a score of 0.5 suggesting no discrimination, similar to random guessing. Thus, a lower AUC-ROC value reflects a model that is not performing well in classifying outcomes, leading to a higher rate of misclassification between the positive and negative instances.

A high AUC-ROC value, typically closer to 1, indicates that the model has a strong ability to correctly classify the two classes, while a low value signals significant limitations in the model's predictive capabilities. This understanding emphasizes the importance of AUC-ROC as a performance metric, particularly in binary classification tasks where distinguishing between classes is crucial for effective decision-making.