Average precision

The area under the precision-recall curve: one number for how well a model finds a rare class.

Other terms from the same lesson

• AUC: Area under the ROC curve: the chance the model scores a random true case above a random false one. 1 is perfect, 0.5 is guessing.
• calibration: Whether a model's probabilities can be taken at face value: of the customers it gives 30%, about 30% really churn.
• false positive rate: The share of real negatives the model wrongly flags, such as the share of loyal customers it says will churn.
• precision-recall curve: A chart of precision against recall as the threshold moves. More telling than the ROC curve when the thing you're looking for is rare.
• ROC curve: A chart of how a classifier trades catching more true cases against raising more false alarms.
• true positive rate: The share of real positives the model catches, such as the share of churners it flags. Another name for recall.