The AI Field Guide / U

Letter U

3 terms, explained without the techno-murk.

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Underfitting

Deeper

When a model is too simple or insufficiently trained to learn the important pattern.

It is the opposite side of overfitting. Imagine trying to describe a winding coastline with one straight line: the rule is so simple that it performs poorly even on the examples it was given, as well as on new ones.

For example

A basic straight-line model fails to capture a strongly curved relationship in the data.

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Unstructured data

Everyday

Information that is not neatly arranged in fixed rows and columns.

Emails, documents, photographs, recordings and videos are commonly called unstructured data. They still have patterns, but need more processing than a tidy database table.

For example

A folder of customer emails is unstructured data.

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Unsupervised learning

Deeper

Learning patterns from data that has not been given human-made answer labels.

The system looks for structure, similarity or useful representations on its own. Much language-model pretraining is often described as self-supervised, a related approach where the data supplies its own learning target.

For example

A system groups news articles by topic without being told the topic names in advance.

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