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FRM Part I · FRM Exam Part I · Machine-Learning Methods

A model predicting credit losses achieves a training mean squared error of 0.5 and a validation mean squared error of 4.8 on held-out data. Which conclusion and remedy is most consistent with these results?

The pattern indicates overfitting, since training error is very low while validation error is far higher. Remedies include regularization or a simpler model. Underfitting would instead produce high error on both the training and validation samples.

  1. AUnderfitting; add more complexity to the model
  2. BOverfitting; apply regularization or simplify the modelCorrect
  3. CGood fit; the gap shows the validation set is too small
  4. DUnderfitting; reduce the size of the training set

Explanation

A very low training error combined with a much higher out-of-sample error signals overfitting: the model has learned noise in the training data. Regularization, reducing complexity or gathering more data helps. Underfitting would show high error on both samples.

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