# Difair Eval

> This benchmark evaluates a language model's ability to disentangle factual gender knowledge from gender bias in masked language modeling. It measures whether a model can correctly predict gendered tokens in gender-specific contexts while remaining gender-neutral in gender-neutral contexts, revealing the trade-off between fairness and factual performance. Use when the user wants to benchmark on DIFAIR, or asks about evaluating this task. Reports GIS.

- Skill: `qhjqhj00/difair-eval` (Agent Skill)
- Install (CLI): `npx skillmds add qhjqhj00/difair-eval`
- Raw SKILL.md: https://api.skillmd.com/api/skills/qhjqhj00/difair-eval/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: qhjqhj00 (https://skillmd.com/u/qhjqhj00)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/qhjqhj00/difair-eval

---


# difair-eval

> DiFair: A Benchmark for Disentangled Assessment of Gender Knowledge and Bias — Zakizadeh et al. (2023) (arXiv:2310.14329, 2023)

## What this evaluates

This benchmark evaluates a language model's ability to disentangle factual gender knowledge from gender bias in masked language modeling. It measures whether a model can correctly predict gendered tokens in gender-specific contexts while remaining gender-neutral in gender-neutral contexts, revealing the trade-off between fairness and factual performance.

## Datasets

- **DIFAIR** — total ?; splits: test (-1); repo https://github.com/mzakizadeh/difair_public

## Metrics

- `GIS` **(primary)** — range: [0, 1]
  - Gender Invariance Score, defined as the harmonic mean of GSS and GNS. Ranges from 0 to 1, where 1.0 indicates ideal behavior (high gender-specific accuracy and zero gender bias in neutral contexts).
- `GSS` — range: [0, 1]
  - Gender-Specific Score measuring the model's ability to predict the correct gender token in gender-specific sentences.
- `GNS` — range: [0, 1]
  - Gender-Neutral Score measuring the model's lack of gender preference when predicting masked words in gender-neutral sentences.
- `Top-k MLM accuracy` — range: [0, 1]
  - Percentage of instances where the correct gender token appears in the model's top-k predicted tokens for the masked position.

## Input / output format

**Input**: Sentences with a single masked token, categorized as either gender-specific (containing a clear gender cue) or gender-neutral (no gender cue). Dates and names are replaced with special tokens to control for spurious correlations.

**Output**: Probability distribution over the vocabulary for the masked position, or top-k predicted tokens.

## Scoring recipe

```python
def compute_gss(preds, golds):
    return sum(1 for p, g in zip(preds, golds) if p == g) / len(golds)

def compute_gns(preds, golds):
    # Measures lack of gender preference; typically 1 - |P(male) - P(female)| or similar neutrality metric
    pass

def compute_gis(gss, gns):
    if gss + gns == 0:
        return 0.0
    return 2 * (gss * gns) / (gss + gns)

# GIS is the harmonic mean of GSS and GNS
```

## Common pitfalls

- Assuming that improving gender neutrality (GNS) automatically preserves factual gender knowledge; debiasing techniques often significantly degrade GSS.
- Overlooking impaired mask-filling capabilities in distilled models, which can artificially inflate GNS by lowering probabilities for all gender tokens rather than genuinely learning neutrality.
- Failing to account for spurious correlations (e.g., date-gender bias) that can artificially lower GIS scores when date ranges shift away from the present day.

## Evidence (verbatim from paper)

> In the ideal case, a model should not favor one gender over another when predicting masked words in gender-neutral sentences, but should have preference for one gender in gender-specific instances. Such a model attains the maximum GIS of 1.0. A random baseline would not perform better than 0 in terms of GIS as it does not have any meaningful gender preference (GSS of 0).

## Citation

```bibtex
@misc{zakizadeh2023difair,
  title={DiFair: A Benchmark for Disentangled Assessment of Gender Knowledge and Bias},
  author={Zakizadeh et al. (2023)},
  year={2023},
  note={arXiv:2310.14329}
}
```

- arXiv: 2310.14329