---
license: cc-by-sa-4.0
language:
  - eu
pretty_name: eusgec-wiki-eval — hand-checked real Basque Wikipedia errors
size_categories:
  - n<1K
tags:
  - grammatical-error-correction
  - gec
  - basque
  - euskara
  - evaluation
  - wikipedia
configs:
  - config_name: default
    data_files:
      - split: errorful
        path: default/errorful-*.parquet
      - split: clean
        path: default/clean-*.parquet
  - config_name: review
    data_files:
      - split: judged
        path: review/judged-*.parquet
---

# eusgec-wiki-eval — real Basque errors from Wikipedia, hand-checked

The small, honest benchmark behind the numbers on
[`itzune/gector-eus-v5`](https://huggingface.co/itzune/gector-eus-v5),
[`itzune/gector-eus-v2`](https://huggingface.co/itzune/gector-eus-v2) and
[`itzune/latxa-8b-gec-lora-v2`](https://huggingface.co/itzune/latxa-8b-gec-lora-v2):
**171 real errors** and **247 clean sentences** taken from actual Basque Wikipedia
revisions and manually verified, so the "clean" half really is clean and the
"error" half really contains the mistake the editor fixed.

Synthetic error-injection benchmarks flatter GEC models; this one does not.

## Composition

| config | split | rows | what it is |
|---|---|---:|---|
| `default` | `errorful` | 171 | real corrections, labelled by error type |
| `default` | `clean` | 247 | sentences no editor touched (false-positive control) |
| `review` | `judged` | 600 | the mined revision pairs these came from, with human verdicts |

```python
from datasets import load_dataset

err = load_dataset("itzune/eusgec-wiki-eval", split="errorful")
clean = load_dataset("itzune/eusgec-wiki-eval", split="clean")
print(err[0])   # source, target, error_type, category, ...
```

### Error types in the `errorful` split

| type | n |
|---|---:|
| `spelling` | 52 |
| `case` | 38 |
| `punctuation` | 28 |
| `inflection` | 17 |
| `from_clean` (regression introduced by an editor) | 12 |
| `multi` | 10 |
| `word_delete` | 6 |
| `word_insert` | 5 |
| `rewrite` | 2 |
| `word_swap` | 1 |

## Fields

`errorful`: `id` (`wk-*`), `nature` (`error`), `category` (`real`), `error_type`,
`domain` (`wikipedia`), `source`, `target`.

`clean`: `sentence`.

`review/judged`: `id`, `shape` (edit shape: `spelling`, `inflection`, `word_swap`,
`rewrite`, `multi`, …), `source`, `target`, `change`, `comment` (Wikipedia edit
summary), `verdict` (`Y`/`N` — is this a real error?), `fixed_target`, `notes`
(human notes from the verification pass).

## How it was built

1. Mine sentence-level revision pairs from the Basque Wikipedia dump
   `euwiki-20261101`, keeping small edits whose corrected sentence survived to the
   latest revision.
2. Sample pairs across edit shapes; for each, render the original and corrected
   sentence and record the edit summary.
3. **Manually verify every row**: does the diff reflect a genuine error (not a
   rewrite, not vandalism, not a stylistic change)? Rows marked `N` were dropped
   from `errorful`; the `review` config keeps them so the noise rate of mined
   Wikipedia edits stays measurable.
4. `category = real`, `domain = wikipedia` distinguishes this slice from the
   synthetic horkonpon slices when pooled.

Every article that contributed here is **excluded** from
[`itzune/wiki-gec-distill-eu`](https://huggingface.co/datasets/itzune/wiki-gec-distill-eu)
and from the horkonpon Wikipedia configs, so the benchmark stays out of training.

## Metrics worth reporting

Score with `eusgec eval` (the scorer used for the published numbers) or any
M²-style scorer:

- **exact match** on `errorful` (sentence fully corrected)
- **token-level P / R / F0.5** (β = 0.5: a false correction is worse than a miss)
- **clean false-positive rate** on `clean` — the number that decides whether a
  browser assistant is usable

Published reference points (int4 ONNX GECToR unless stated):

| system | exact | P | R | F0.5 | clean FP |
|---|---:|---:|---:|---:|---:|
| GECToR v2 | — | — | — | 15.7 | 0.0% |
| GECToR v4.1 + cascade | 8.2% | 55.6 | 7.9 | 25.2 | 0.0% |
| GECToR v5 + cascade | 14.6% | 71.7 | 17.4 | 44.1 | 1.2% |
| latxa-8b-gec-lora-v2, margin −1 | 28.1% | 75.3 | 30.5 | 58.2 | 2.8% |

## Limitations

- **Small**: 171 errorful sentences. One sentence = 0.6 points of exact match;
  differences under ~2 points are noise.
- **Wikipedia register only** — encyclopedic prose, not news, not social media.
- Labels are single-annotator; the `review` verdicts are one Basque speaker's
  judgement, not a multi-annotator consensus.
- Wikipedia corrections include stylistic preferences; `from_clean` rows keep the
  handful of "corrections" that introduced an error, which most systems cannot
  catch and which depress every score slightly.

## Licensing and attribution

CC-BY-SA-4.0 — derived from the Basque Wikipedia dump `euwiki-20261101`.
The `review` config includes edit summaries and revision context from Wikipedia;
article titles are intentionally not stored, but the sentences are verbatim
Wikipedia content, so attribution to the project and share-alike both apply.

## Citation

```bibtex
@misc{ezpeleta2026eusgecwikieval,
  author       = {Xabi Ezpeleta},
  title        = {eusgec-wiki-eval: a hand-checked benchmark of real Basque
                  grammatical errors from Wikipedia},
  year         = {2026},
  publisher    = {Hugging Face},
  howpublished = {\url{https://huggingface.co/datasets/itzune/eusgec-wiki-eval}}
}
```

## References

- Basque Wikipedia dump `euwiki-20261101`,
  [dumps.wikimedia.org/euwiki](https://dumps.wikimedia.org/euwiki/) (CC-BY-SA-4.0)
- Scorer and baselines: [itzune/gector-eus-v2](https://github.com/itzune/gector-eus-v2)
  (`scripts/eval_onnx.py`, `eusgec eval`)
- Bryant, C., Felice, M., Briscoe, T. (2017). *Automatic Annotation and Evaluation
  of Error Types in Learner Corpora* — M² alignment convention.
- Omelianchuk, K. et al. (2020). *GECToR — Tag, Not Rewrite.* BEA@ACL.
  [arXiv:2005.12592](https://arxiv.org/abs/2005.12592)
- Evaluated systems: [`itzune/gector-eus-v5`](https://huggingface.co/itzune/gector-eus-v5),
  [`itzune/gector-eus-v2`](https://huggingface.co/itzune/gector-eus-v2),
  [`itzune/latxa-8b-gec-lora-v2`](https://huggingface.co/itzune/latxa-8b-gec-lora-v2)