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

# Bias

> Detect bias across protected attributes using guardian-based analysis

## Overview

The **Bias** metric measures bias in AI responses across five protected attributes using a guardian-based detection system. For each interaction, a `Guardian` evaluates whether the response exhibits bias toward any protected group.

## Protected attributes

Gaussia evaluates bias across these attributes by default:

| Attribute            | Description                                |
| -------------------- | ------------------------------------------ |
| `gender`             | Gender identity and expression             |
| `race`               | Race and ethnic background                 |
| `religion`           | Religious beliefs and affiliations         |
| `nationality`        | National origin and citizenship            |
| `sexual_orientation` | Sexual orientation and romantic attraction |

## Usage

```python theme={null}
from gaussia.metrics.bias import Bias
from gaussia.guardians import MyGuardian  # Your Guardian implementation

results = Bias.run(
    MyRetriever,
    guardian=MyGuardian,
)

for r in results:
    for rate in r.attribute_rates:
        print(f"{rate.protected_attribute}: {rate.rate:.3f} ({rate.k_biased}/{rate.n_samples})")
```

## Parameters

| Parameter          | Type              | Default             | Description                       |
| ------------------ | ----------------- | ------------------- | --------------------------------- |
| `retriever`        | `type[Retriever]` | *required*          | Retriever class                   |
| `guardian`         | `type[Guardian]`  | *required*          | Guardian class for bias detection |
| `statistical_mode` | `StatisticalMode` | `FrequentistMode()` | Statistical computation mode      |

## Output schema

### BiasMetric

| Field                   | Type                      | Description                       |
| ----------------------- | ------------------------- | --------------------------------- |
| `session_id`            | `str`                     | Session identifier                |
| `assistant_id`          | `str`                     | Assistant identifier              |
| `attribute_rates`       | `list[AttributeBiasRate]` | Bias rate per protected attribute |
| `guardian_interactions` | `dict`                    | Per-attribute interaction details |

### AttributeBiasRate

| Field                 | Type            | Description                    |
| --------------------- | --------------- | ------------------------------ |
| `protected_attribute` | `str`           | The attribute being evaluated  |
| `n_samples`           | `int`           | Total interactions evaluated   |
| `k_biased`            | `int`           | Number of biased interactions  |
| `rate`                | `float`         | Bias rate (0–1)                |
| `ci_low`              | `float \| None` | Lower CI bound (Bayesian only) |
| `ci_high`             | `float \| None` | Upper CI bound (Bayesian only) |

## Guardian interface

To use the Bias metric, implement a `Guardian` subclass:

```python theme={null}
from gaussia.core.guardian import Guardian

class MyGuardian(Guardian):
    def is_biased(self, question, answer, attribute, context):
        # Return a GuardianResult with is_biased, attribute, and certainty
        ...
```

<Note>
  Requires the `bias` extra: `pip install "gaussia[bias]"`.
</Note>