Generalization is a model’s ability to perform accurately on previously unseen examples. It requires low loss not only on labeled training data but also on new, unseen test data. This ability distinguishes useful machine-learning algorithms from systems that merely fit their training examples. section 1.1
Evaluate generalization by comparing performance across:
- Training data, whose labels are already available and support fitting the model. section 1.1
- Unseen test data, where low loss indicates that learned behavior extends beyond the training set. section 1.1












