Sample-Size Scaling of the African Languages NLI Evaluation
Paper · 2026 · Anuj Tiwari, Oluwapelumi Ogunremu, Terry Oko-odion et al.
Summary
Labelled data for African languages is scarce, and it is unclear whether more annotated examples reliably yield better or more trustworthy NLI results. The authors study this with the AfriXNLI benchmark across 16 African languages. They compare two multilingual encoders of about 0.6B parameters each: XLM-R Large fine-tuned on XNLI and AfroXLM-R Large. The abstract describes the study as a training-data scaling study, but the experimental sections show something different. The models are never retrained. Instead, the authors randomly subsample the AfriXNLI test splits at sizes from 50 to 500 examples and repeat this several times. They then report the mean and standard deviation of accuracy, precision and F1. The findings concern how stable evaluation is, not how much models learn. Scaling turns out to be strongly language-dependent and often non-monotonic. Small subsets tend to overstate accuracy, and variance stays high below roughly 300 examples. The paper therefore argues that African NLI benchmarks should report variance across subsamples and use sufficiently large, language-aware test sets.
Key points
- Setup: The study covers 16 AfriXNLI languages and two models, XLM-R Large (XNLI-fine-tuned) and AfroXLM-R Large. Test subsets range from 50 to 500 examples, with repeated random draws at each size.
- Variance: Accuracy variance is highest at 50–100 samples. It levels off at about 300 samples for both models.
- Language-specific trends:
- Yoruba starts with high accuracy at 50 examples and declines steadily as more samples are added.
- Kinyarwanda improves slightly up to about 150 examples, then flattens.
- Both patterns appear under both models.
- Saturation points: These mark where mean accuracy stays within ±0.5%. They range from about 200–250 samples for Shona, Xhosa and Yoruba under XLM-R up to 450 for several languages. Wolof never stabilises within 500 samples under XLM-R.
- Recommendations:
- Report mean ± SD over multiple subsamples.
- Add per-class metrics.
- Use at least 300 evaluation samples, and treat smaller sets as high-noise.
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 works
🧭 Topics 2Research subjects and languages the work is about.Reasoning · 1,426 worksEvaluation & benchmarks · 1,220 works
Cite
Cite as Anuj Tiwari, Oluwapelumi Ogunremu, Terry Oko-odion, Jesujuwon Egbewale and Hannah Sopuruchi Nwokocha. 2026. Sample-Size Scaling of the African Languages NLI Evaluation. Proceedings of the 7th Workshop on African Natural Language Processing (AfricaNLP 2026).
@inproceedings{tiwari2026sample,
title = {{Sample-Size Scaling of the African Languages NLI Evaluation}},
author = {Anuj Tiwari, Oluwapelumi Ogunremu, Terry Oko-odion, Jesujuwon Egbewale and Hannah Sopuruchi Nwokocha},
booktitle = {Proceedings of the 7th Workshop on African Natural Language Processing (AfricaNLP 2026)},
year = {2026},
doi = {10.18653/v1/2026.africanlp-main.22},
url = {https://doi.org/10.18653/v1/2026.africanlp-main.22}
}References
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