Overfitting and Regularization: Dropout, Weight Decay and Early Stopping

~13 min read

A model that memorizes its training data instead of learning general patterns is overfit — great on training loss, bad on new data. Dropout, weight decay and early stopping are three standard ways to prevent it.

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Key points

  • Overfitting is when training loss keeps improving but validation/test performance stalls or worsens — the model memorized training quirks instead of learning generalizable patterns
  • Dropout randomly zeros out a fraction of neurons every training step, forcing the network to learn redundant, more robust representations
  • Weight decay (L2 regularization) adds a penalty for large weights to the loss, encouraging smoother functions that generalize better
  • Early stopping tracks validation loss and halts training once it stops improving, even if training loss is still falling — directly targeting the overfitting signature
  • Real training runs typically combine all three: dropout and weight decay slow overfitting during training, early stopping is the final safety net