Underfitting
Publication dates and source age
Sources counted: 2
Publication dates are unavailable.
Assessed at this edition's evidence cutoff: 2026-09-15. 18-month boundary: 2025-03-15.
Some publication dates are unknown; the newest dated source may not be the newest source overall.
Publication age does not tell us whether a claim is still valid. Reading an old source again does not make its publication date newer. An update date does not establish that the passage we used was updated.
Open in the glossary Reading notes · Structured record
In plain language
When a model has not captured enough of the pattern even in its training examples. [1] [2]
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Limits & distinctions
Underfitting is not a synonym for a small model. It describes an inadequate fit for the task and available data. [1]
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A fuller explanation
Possible causes include an unsuitable model structure, missing useful inputs or too little training. These are different problems, so simply adding more examples may not address the cause. [1]
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How it relates to the map
Ask whether the error already appears in training before comparing performance on new data. [2]
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https://theaiatlas.org/ideas/underfitting/
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Sources and what we read
1. Machine Learning Glossary
Publication dates and source age
Sources counted: 1
Publication dates are unavailable.
Assessed at this edition's evidence cutoff: 2026-09-15. 18-month boundary: 2025-03-15.
Some publication dates are unknown; the newest dated source may not be the newest source overall.
Publication age does not tell us whether a claim is still valid. Reading an old source again does not make its publication date newer. An update date does not establish that the passage we used was updated.
Read the underfitting entry and its listed causes. Updated date follows the glossary page; initial publication date is unspecified. This is a diagnostic concept, not a finding about any listed model.
2. Overfitting
Publication dates and source age
Sources counted: 1
Publication dates are unavailable.
Assessed at this edition's evidence cutoff: 2026-09-15. 18-month boundary: 2025-03-15.
Some publication dates are unknown; the newest dated source may not be the newest source overall.
Publication age does not tell us whether a claim is still valid. Reading an old source again does not make its publication date newer. An update date does not establish that the passage we used was updated.
Read training versus new-data performance, the underfitting comparison and generalization curves. Illustrative curves are not evidence about a particular model.
Edition and machine-readable evidence
Content version 0.20.0. Evidence cutoff 2026-09-15; this does not mean every source was read on that day.
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