The generalisation error is the error a model has on unseen data. We rarely have a model for unseen data, and we only have samples to deal with, however we can minimise the empirical error which we have control over.
The generalisation error is the error a model has on unseen data. We rarely have a model for unseen data, and we only have samples to deal with, however we can minimise the empirical error which we have control over.