PEFT Gains Need Hidden Baselines: Rank and Optimizer Sweeps Change LoRA Conclusions

Ding Wu


Abstract
New parameter-efficient fine-tuning (PEFT) methods are often credited with gains against a single default LoRA configuration, even though inexpensive tuning of vanilla LoRA may change the comparison. We present a deliberately small, descriptive case study of two claims: adaptive rank allocation with AdaLoRA and LoRA-specific optimization with LoRA-RITE. Using RoBERTa-base on capped subsets of three GLUE classification tasks, we compare each method with a pre-specified vanilla LoRA control sweep. AdaLoRA beats fixed LoRA at rank 8 in 4 of 7 dataset-seed cells, but beats the best tested fixed rank in only 1 of 7. LoRA-RITE beats default AdamW in 3 of 6 cells, but tuned AdamW in only 1 of 6. Several SST-2 runs collapse to the majority label, so these counts are illustrative rather than population-level estimates. The practical contribution is an attribution protocol: report modest vanilla rank/learning-rate sweeps, per-cell margins, instability checks, and budget accounting before attributing gains to a specialized PEFT mechanism.
Anthology ID:
2026.insights-1.17
Volume:
Proceedings of the Seventh Workshop on Insights from Negative Results in NLP
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
João Sedoc, Raphael Shu, Aleksandr Drozd, Arjun Akula, Anna Rogers, Salvatore Giorgi, Adrian Benton
Venues:
insights | WS
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Publisher:
Association for Computational Linguistics
Note:
Pages:
127–132
Language:
URL:
https://aclanthology.org/2026.insights-1.17/
DOI:
Bibkey:
Cite (ACL):
Ding Wu. 2026. PEFT Gains Need Hidden Baselines: Rank and Optimizer Sweeps Change LoRA Conclusions. In Proceedings of the Seventh Workshop on Insights from Negative Results in NLP, pages 127–132, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
PEFT Gains Need Hidden Baselines: Rank and Optimizer Sweeps Change LoRA Conclusions (Wu, insights 2026)
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https://aclanthology.org/2026.insights-1.17.pdf
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 2026.insights-1.17.SupplementaryMaterial.txt