Artificial Intelligence

What is Overfitting?

Quick answer

When a machine learning model learns its training data too closely, including noise, and performs poorly on new, unseen data.

Overfitting, explained

An overfitted model is like a student who memorizes past exam answers instead of understanding the subject: it scores perfectly on familiar questions but struggles with new ones. In practice, it shows very high accuracy on training data and noticeably lower accuracy on validation or test data.

Overfitting is more likely when a model is very complex relative to the amount of training data. Common remedies include gathering more data, simplifying the model, regularization techniques that penalize complexity, dropout in neural networks, early stopping during training, and cross-validation. The opposite problem, underfitting, happens when a model is too simple to capture real patterns. Good machine learning practice balances the two.

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