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AI & Machine Learning · Foundational

Test Dataset

Data kept completely separate until the end to measure a final model's generalization performance.

Definition

The test set should be used once, after all modeling choices are final, to estimate how the model will perform on unseen data. Reusing it for tuning leaks information and inflates results. It must come from the same distribution as production data.

Exam tip

Using the test set to choose hyperparameters is a classic exam trap.

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