# Validation set

> The subset of the dataset that performs initial evaluation against a trained model. Typically, you evaluate the trained model against the validation set several times before evaluating the model against the test set.

The subset of the [dataset](https://wiki.g15e.com/pages/Dataset%20(machine%20learning.txt)) that performs initial evaluation against a trained [model](https://wiki.g15e.com/pages/Model%20(machine%20learning.txt)). Typically, you evaluate the trained model against the validation set several times before evaluating the model against the [test set](https://wiki.g15e.com/pages/Test%20set.txt).

Traditionally, you divide the examples in the dataset into the following three distinct subsets:

- a [training set](https://wiki.g15e.com/pages/Training%20data.txt)
- a validation set
- a [test set](https://wiki.g15e.com/pages/Test%20set.txt)

Ideally, each example in the dataset should belong to only one of the preceding subsets. For example, a single example shouldn't belong to both the training set and the validation set.[^1]

## Footnotes

[^1]: https://developers.google.com/machine-learning/glossary#validation-set