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Underfitting

A model fails to capture the relationships needed for its task adequately and therefore produces weak predictions.

Machine learning

What does underfitting mean?

Underfitting occurs when a model fails to capture the relationships needed for its task adequately. Weak results may then appear even on training examples. Possible causes include unsuitable input features, insufficient model capacity or an inappropriate training setup. Investigation considers training and assessment results alongside the data, targets and settings. A larger dataset alone does not automatically fix the missing representation of those relationships.

Suppose a fictional service-planning model predicts almost the same working duration for brief checks and extensive repairs. The team investigates whether the type of work is available as input and whether the durations used as target values describe the same scope of work. It then checks whether the chosen model form and training can capture the relevant differences. Suitable cases from learning and separate assessment are compared for this purpose. The next variant is developed from these findings instead of merely feeding additional examples into the unchanged process.

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