Evaluating the performance of classification models
When we make predictions using our model, as we did earlier, how do we know whether the predictions are good or not? We need to be able to evaluate how well our model performs. Evaluation metrics commonly used in binary classification include prediction accuracy and error, precision and recall, and area under the precision-recall curve, the receiver operating characteristic (ROC) curve, area under ROC curve (AUC), and F-measure.
Accuracy and prediction error
The prediction error for binary classification is possibly the simplest measure available. It is the number of training examples that are misclassified, divided by the total number of examples. Similarly, accuracy is the number of correctly ...