> ## Documentation Index
> Fetch the complete documentation index at: https://docs.openlayer.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Feature values

> Learn how to use the feature values test

## Definition

The feature values test allows you to define the expected range of values for a feature. For categorical features,
you can define the expected categories.

## Taxonomy

* **Task types**: Tabular classification, tabular regression.
* **Availability**: development (Continuously evaluate your models and datasets as you iterate on their versions.)
  and monitoring (Monitor a model in production, measure its health, check for drifts and set up alerts.).

## Why it matters

* Ensuring that the values of a feature are always within a defined range is important to validate the hypotheses around the data. For example, for a feature such as `Age`, negative values would be invalid and signal an issue with the data collection/ingestion process.
* Values outside the expected range can also be a sign of data drift.
* For some categorical features, it is important to ensure that the values are always within the expected categories.

## Test configuration examples

If you are writing a `tests.json`, here are a few valid configurations for the character length test:

```json Development theme={null}
[
  {
    "name": "Feature 'Year' less than 2026",
    "description": "Asserts that the values of the feature 'Year' are within the specified range",
    "type": "integrity",
    "subtype": "featureValueValidation",
    "thresholds": [
      {
        "insightName": "featureProfile",
        "insightParameters": [
          { "name": "name", "value": "Year" }
        ],
        "measurement": "max",
        "operator": "<=",
        "value": 2026
      }
    ],
    "subpopulationFilters": null,
    "mode": "development",
    "usesValidationDataset": true,
    "usesTrainingDataset": false,
    "usesMlModel": false,
    "syncId": "b4dee7dc-4f15-48ca-a282-63e2c04e0689"
  }
]
```

```json Monitoring theme={null}
[
  {
    "name": "Feature 'Year' less than 2026",
    "description": "Asserts that the values of the feature 'Year' are within the specified range",
    "type": "integrity",
    "subtype": "featureValueValidation",
    "thresholds": [
      {
        "insightName": "featureProfile",
        "insightParameters": [{ "name": "name", "value": "Year" }],
        "measurement": "max",
        "operator": "<=",
        "value": 2026
      }
    ],
    "subpopulationFilters": null,
    "mode": "monitoring",
    "usesProductionData": true,
    "evaluationWindow": 3600,
    "delayWindow": 0,
    "syncId": "b4dee7dc-4f15-48ca-a282-63e2c04e0689"
  }
]
```

## Related

* [Feature drift test](https://docs.openlayer.com/tests/consistency/feature-drift-count).


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