Lightweight but Linguistically Fair? Quantisation Robustness across Bavarian, German, and English
Organizations: Leibniz Supercomputing Centre (LRZ), Garching, Germany · Bavarian Academy of Sciences and Humanities, Munich, Germany · TUM University Hospital and Technical University of Munich, Munich, Germany
Abstract
Post-training quantisation reduces the memory cost of large language models, but it remains unclear whether compression preserves language skills of regional varieties as reliably as their standard-language counterparts. We study this question for Bavarian, Standard German, and English using BAVGROUND, a multiple-choice benchmark, where 206 source questions are aligned across all three languages. Across 14 open-weight 7B--10B instruction models, we compare BF16 with 8-bit GPTQ and two 4-bit settings, GPTQ and AWQ. Eight-bit GPTQ remains close to BF16 and largely preserves the relative behaviour of the three languages, while 4-bit quantisation was found to be much less stable. The two 4-bit methods reduce average accuracy by about 1.4--1.5 percentage points and change 11.9--16.0% of BF16 decisions, with changes concentrated on examples where the BF16 model is already uncertain. This instability does not translate into a consistent Bavarian disadvantage. Although Bavarian, a low-resource dialect, has lower baseline accuracy than German and English, the language most affected at 4 bits varies across models and quantisation methods. Calibration further shapes these cross-language effects: the relative Bavarian--German effect changes with calibration language, while changing the calibration source has little average effect on GPTQ-4 but can affect AWQ-4 much more strongly. Free-form evaluation on five models further shows that 4-bit compression can degrade generated responses even in settings where multiple-choice accuracy changes only modestly, while 8-bit GPTQ remains comparatively stable. Overall, our results show that quantisation robustness for regional language varieties depends on the model, quantisation method, calibration data, and evaluation setting, and cannot be measured by aggregate multilingual accuracy alone.
Figures & tables
| Model | BF16 | GPTQ-8 | GPTQ-4 | AWQ-4 | Best |
|---|---|---|---|---|---|
| Aya Expanse 8B | 58.7 | 58.4 (-0.3) | 53.2 (-5.5) | 58.7 (+0.0) | BF16 |
| EuroLLM 9B | 68.9 | 69.4 (+0.5) | 65.2 (-3.7) | 64.7 (-4.2) | GPTQ-8 |
| GENBA-10B | 57.6 | 57.8 (+0.2) | 51.0 (-6.6) | 56.5 (-1.1) | GPTQ-8 |
| Gemma 2 9B | 55.2 | 55.5 (+0.3) | 55.8 (+0.6) | 58.4 (+3.2) | AWQ-4 |
| Granite 3.0 8B | 62.8 | 62.6 (-0.2) | 62.5 (-0.3) | 57.1 (-5.7) | BF16 |
| LLaMmlein 7B | 57.1 | 57.8 (+0.6) | 57.0 (-0.2) | 58.7 (+1.6) | AWQ-4 |
| Setting | BAR | DE | EN | ||
|---|---|---|---|---|---|
| GPTQ-8 | -0.1 | 0.0 | +0.2 | -0.1 | -0.3 |
| GPTQ-4 | -1.9 | -0.5 | -1.9 | -1.4 | 0.0 |
| AWQ-4 | -1.1 | -2.1 | -1.1 | +1.0 | 0.0 |
| GPTQ-4 | AWQ-4 | |||
|---|---|---|---|---|
| Calibration | BAR | BAR–DE | BAR | BAR–DE |
| Balanced | -1.82 | -0.85 | +0.97 | +4.25 |
| English only | -2.55 | -1.09 | +1.09 | +3.88 |
| German only | -3.52 | -3.16 | -1.33 | +3.28 |
| Bavarian only | -0.36 | +0.12 | -0.36 | +1.82 |
| Low margin (D1) | High margin (D10) | |||
|---|---|---|---|---|
| Setting | Change | Loss | Change | Loss |
| GPTQ-8 | 10.16 | 3.23 | 0.00 | 0.00 |
| GPTQ-4 | 39.95 | 15.94 | 1.62 | 0.69 |
| AWQ-4 | 43.42 | 16.28 | 1.27 | 0.23 |
| Setting | BF16 win | Quant. win | Tie | Not worse | Net quant. | |
|---|---|---|---|---|---|---|
| GPTQ-8 | 3047 | 13.1 | 10.8 | 76.1 | 86.9 | -2.3 |
| GPTQ-4 | 3049 | 36.2 | 29.8 | 33.9 | 63.7 | -6.4 |
| AWQ-4 | 3048 | 45.7 | 28.1 | 26.1 | 54.2 | -17.6 |
Appendix figures & tables25 assets
Supplementary material from the paper’s appendix.
Appendix
| Setting | vs. BF16 | 95% CI | Source clusters | Paired rows |
|---|---|---|---|---|
| GPTQ-8 | +0.03 | [-0.14, +0.21] | 206 | 8,652 |
| GPTQ-4 | -1.47 | [-2.21, -0.72] | 206 | 8,652 |
| AWQ-4 | -1.42 | [-2.21, -0.61] | 206 | 8,652 |
| Model | BF16 | Best quantised | |
|---|---|---|---|
| Qwen2 7B Instruct | 63.8 | 63.6 (GPTQ-8) | -0.2 |
| Qwen2.5 3B Instruct | 60.7 | 60.4 (GPTQ-8) | -0.3 |
| Qwen2.5 7B Instruct | 63.1 | 65.4 (GPTQ-4) | +2.3 |
| Qwen3 4B | 51.9 | 51.6 (GPTQ-8) | -0.3 |
| Qwen3 8B | 48.1 | 56.6 (GPTQ-4) | +8.6 |
| Setting | Contrast | Estimate | 90% CI | 95% CI | Equivalent |
|---|---|---|---|---|---|
| GPTQ-8 | BAR–DE | -0.07 | [-0.73, +0.59] | [-0.83, +0.69] | Yes |
| GPTQ-8 | BAR–EN | -0.35 | [-1.04, +0.31] | [-1.21, +0.45] | Yes |
| GPTQ-4 | BAR–DE | -1.42 | [-3.43, +0.59] | [-3.81, +0.90] | No |
| GPTQ-4 | BAR–EN | +0.00 | [-2.08, +2.18] | [-2.46, +2.67] | No |
| AWQ-4 | BAR–DE | +1.01 | [-1.35, +3.40] | [-1.94, +3.88] | No |
| AWQ-4 | BAR–EN | +0.03 | [-2.32, +2.50] | [-2.77, +3.02] | No |
| Setting | Contrast | pp | pp | pp |
|---|---|---|---|---|
| GPTQ-8 | BAR–DE | Yes | Yes | Yes |
| GPTQ-8 | BAR–EN | No | Yes | Yes |
| GPTQ-4 | BAR–DE | No | No | No |
| GPTQ-4 | BAR–EN | No | No | Yes |
| AWQ-4 | BAR–DE | No | No | No |
| AWQ-4 | BAR–EN | No | No | Yes |
| Setting | BAR DE | Similar | BAR DE |
|---|---|---|---|
| GPTQ-8 | 6 | 2 | 6 |
| GPTQ-4 | 9 | 1 | 4 |
| AWQ-4 | 6 | 1 | 7 |
| Model | Quantiser | BAR | DE | EN | BAR-DE | BAR-EN |
|---|---|---|---|---|---|---|
| Aya Expanse 8B | GPTQ-8 | +0.0 | -0.5 | -0.5 | +0.5 | +0.5 |
| Aya Expanse 8B | GPTQ-4 | -7.8 | +0.0 | -8.7 | -7.8 | +1.0 |
| Aya Expanse 8B | AWQ-4 | +0.0 | +2.4 | -2.4 | -2.4 | +2.4 |
| EuroLLM 9B | GPTQ-8 | +1.0 | +0.5 | +0.0 | +0.5 | +1.0 |
| EuroLLM 9B | GPTQ-4 | -4.9 | -1.9 | -4.4 | -2.9 | -0.5 |
| EuroLLM 9B | AWQ-4 | -1.5 | -8.3 | -2.9 | +6.8 | +1.5 |
| Domain | Prompt BAR/DE | Prompt BAR/EN | Prompt DE/EN | Gold BAR/DE | Gold BAR/EN |
|---|---|---|---|---|---|
| Building & Sacred Heritage | 1.04 | 1.18 | 1.14 | 1.09 | 1.30 |
| Language | 1.00 | 1.10 | 1.09 | 0.94 | 1.06 |
| Politics | 1.03 | 1.17 | 1.14 | 1.01 | 1.31 |
| Historical | 1.05 | 1.17 | 1.12 | 1.07 | 1.20 |
| Landscape | 1.03 | 1.14 | 1.11 | 1.05 | 1.22 |
| Living Traditions & Customs | 1.03 | 1.18 | 1.15 | 1.03 | 1.38 |
| Subset | BF16 | GPTQ-8 | GPTQ-4 | AWQ-4 |
|---|---|---|---|---|
| GEN | 63.4 | +0.2 | -1.4 | -1.4 |
| GRD | 57.9 | -0.1 | -1.5 | -1.4 |
| Domain | BF16 | GPTQ-8 | GPTQ-4 | AWQ-4 |
|---|---|---|---|---|
| Language | 40.5 | -0.4 | -2.2 | -1.9 |
| Building & Sacred Heritage | 57.1 | +0.0 | -2.4 | -3.1 |
| Politics | 61.7 | -0.3 | +0.4 | -0.1 |
| Arts & Identity | 62.7 | +0.2 | -1.6 | -0.9 |
| Culinary | 62.8 | +0.3 | +0.0 | +0.1 |
| Landscape | 63.4 | +0.3 | -2.4 | -1.6 |
| Model | Checkpoint identifier |
|---|---|
| GENBA-10B | GENBA-10B-instruct Hoffmann et al. (2025) |
| Llama 3.1 Instruct | meta-llama/Llama-3.1-8B-Instruct |
| EuroLLM Instruct | utter-project/EuroLLM-9B-Instruct |
| Qwen2.5 Instruct | Qwen/Qwen2.5-7B-Instruct |
| Mistral Instruct v0.3 | mistralai/Mistral-7B-Instruct-v0.3 |
| Gemma 2 IT | google/gemma-2-9b-it |
| Calibration | Documents | EN tokens | DE tokens | BAR tokens |
|---|---|---|---|---|
| Balanced | 1,383 | 83,416 | 83,423 | 83,607 |
| EN-only | 1,369 | 250,238 | – | – |
| DE-only | 1,387 | – | 250,291 | – |
| BAR-only | 1,363 | – | – | 250,106 |
| Setting | Calibration | EN | DE | BAR | BAR–DE | BAR–EN |
|---|---|---|---|---|---|---|
| GPTQ-4 | Balanced | -2.91 | -0.97 | -1.82 | -0.85 | +1.09 |
| GPTQ-4 | English only | -2.79 | -1.46 | -2.55 | -1.09 | +0.24 |
| GPTQ-4 | German only | -0.12 | -0.36 | -3.52 | -3.16 | -3.40 |
| GPTQ-4 | Bavarian only | -0.85 | -0.49 | -0.36 | +0.12 | +0.49 |
| AWQ-4 | Balanced | -1.70 | -3.28 | +0.97 | +4.25 | +2.67 |
| AWQ-4 | English only | -1.33 | -2.79 | +1.09 | +3.88 | +2.43 |
| Setting | Calibration | Neg. | Similar | Pos. | Range |
|---|---|---|---|---|---|
| GPTQ-4 | Balanced | 3 | 0 | 1 | |
| GPTQ-4 | English only | 2 | 0 | 2 | |
| GPTQ-4 | German only | 4 | 0 | 0 | |
| GPTQ-4 | Bavarian only | 1 | 1 | 2 | |
| AWQ-4 | Balanced | 0 | 1 | 3 | |
| AWQ-4 | English only | 0 | 1 | 3 |
| Model | Quantiser | Balanced | EN-only | DE-only | BAR-only |
|---|---|---|---|---|---|
| EuroLLM 9B | GPTQ-4 | -2.91 | -2.43 | -6.80 | +0.97 |
| GENBA-10B | GPTQ-4 | +1.94 | +0.97 | -0.97 | +0.97 |
| Llama 3.1 8B | GPTQ-4 | -0.49 | +0.97 | -0.49 | 0.00 |
| Qwen2.5 7B | GPTQ-4 | -1.94 | -3.88 | -4.37 | -1.46 |
| EuroLLM 9B | AWQ-4 | +6.80 | +5.34 | +8.74 | +5.83 |
| GENBA-10B | AWQ-4 | +6.31 | +6.31 | +2.91 | +3.40 |
| Setting | Instruction | Wikimedia | |
|---|---|---|---|
| Focused: 4 models, 3 seeds, all calibration conditions | |||
| GPTQ-4 | 62.25 | 62.43 | +0.18 |
| AWQ-4 | 61.86 | 63.11 | +1.25 |
| Overall | 62.06 | 62.77 | +0.72 |
| Finite paired runs: balanced calibration, seed 42 | |||
| GPTQ-4 (14 models) | 58.55 | 58.16 | -0.39 |
| Predictor | Log-odds | OR | |
|---|---|---|---|
| BF16 selected-answer margin | -3.263 | 0.038 | -28.18 |
| BF16 correct-answer margin | -0.040 | 0.961 | -0.92 |
| Prompt tokens | +0.243 | 1.275 | +1.87 |
| Gold-answer tokens | -0.549 | 0.577 | -3.80 |
| German vs. Bavarian | -0.065 | 0.938 | -1.13 |
| English vs. Bavarian | +0.002 | 1.002 | +0.02 |
| Domain | Setting | Acc. | Loss | Gain | Change |
|---|---|---|---|---|---|
| Building & Sacred Heritage | GPTQ-8 | +0.0 | 0.3 | 0.3 | 1.0 |
| Building & Sacred Heritage | GPTQ-4 | -2.4 | 5.7 | 3.3 | 12.6 |
| Building & Sacred Heritage | AWQ-4 | -3.1 | 7.5 | 4.4 | 18.0 |
| Language | GPTQ-8 | -0.4 | 0.5 | 0.1 | 1.0 |
| Language | GPTQ-4 | -2.2 | 5.6 | 3.4 | 15.2 |
| Language | AWQ-4 | -1.9 | 7.3 | 5.4 | 20.7 |
| Item | Lang. | Domain | Losses | Gains | Loss Rate | Change Rate |
|---|---|---|---|---|---|---|
| politics_012 | BAR | Politics | 9 | 2 | 21.4 | 26.2 |
| building_and_sacred_heritage_025 | BAR | Building/Sacred Heritage | 9 | 0 | 21.4 | 23.8 |
| culinary_002 | EN | Culinary | 8 | 3 | 19.0 | 28.6 |
| culinary_022 | EN | Culinary | 8 | 0 | 19.0 | 21.4 |
| language_024 | DE | Language | 8 | 1 | 19.0 | 21.4 |
| historical_007 | BAR | Historical | 7 | 5 | 16.7 | 35.7 |
| Language | Setting | Quant. not worse | Net quant. | |
|---|---|---|---|---|
| BAR | GPTQ-8 | 997 | 86.1 | -2.5 |
| BAR | GPTQ-4 | 999 | 59.8 | -7.8 |
| BAR | AWQ-4 | 998 | 51.2 | -18.8 |
| DE | GPTQ-8 | 1021 | 86.8 | -1.3 |
| DE | GPTQ-4 | 1022 | 59.7 | -13.7 |
| DE | AWQ-4 | 1021 | 52.2 | -21.7 |
| Model | Quant. not worse | Net quant. | |
|---|---|---|---|
| EuroLLM 9B | 1850 | 77.2 | -5.8 |
| Mistral 7B | 1824 | 75.3 | -5.9 |
| Llama 3.1 8B | 1798 | 64.3 | -6.9 |
| Qwen2.5 7B | 1835 | 58.1 | -12.1 |
| GENBA-10B | 1837 | 66.3 | -13.0 |
| Model | Setting | Acc. | Mem. | Red. | Items/s |
| EuroLLM 9B | BF16 | 68.9 | 23.2 | 0 | 2.42 |
| EuroLLM 9B | GPTQ-8 | 69.4 | 14.2 | 38 | 0.98 |
| EuroLLM 9B | GPTQ-4 | 65.2 | 10.2 | 56 | 1.31 |
| Mistral 7B v0.3 | BF16 | 66.8 | 19.2 | 0 | 3.11 |
| Mistral 7B v0.3 | GPTQ-8 | 66.3 | 11.4 | 41 | 1.69 |
| Mistral 7B v0.3 | GPTQ-4 | 67.2 | 7.9 | 59 | 1.70 |
| Criterion | Configurations |
|---|---|
| memory reduction, within 1 pp of BF16 | 11 |
| memory reduction, within 2 pp of BF16 | 15 |
| Quantised accuracy BF16 accuracy | 19 |
| GPTQ-4 accuracy GPTQ-8 | 9/14 |
| GPTQ-4 accuracy GPTQ-8 | 5/14 |
| Component | Captured setting |
|---|---|
| Accelerator | NVIDIA GH200 reported by nvidia-smi ; 97,871 MiB device memory (approximately 95.6 GiB), driver 580.95.05, and 900 W power limit. |
| Operating system | Linux on aarch64 ; kernel 6.2.0-1015-nvidia-64k . |
| Python | Python 3.10.12. |
| Core packages | torch 2.13.0, transformers 5.14.1, accelerate 1.14.0, GPTQModel 7.3.2, bitsandbytes 0.50.0, numpy 2.2.6, pandas 2.3.3, scipy 1.15.3, nvidia-ml-py 13.610.43. |
| Inference backend | Hugging Face Transformers with automatic device mapping. Quantised checkpoints are loaded as Hugging Face-compatible GPTQ or AWQ checkpoints. |
| Aspect | Setting |
|---|---|
| Evaluation config | configs/evaluation/bavground_full.yaml ; languages en , de , and bar ; protocols option_text_avg , letter , and generate_letter_and_text . |
| Runtime parameters | Batch size 1, maximum sequence length 4096, maximum generation length 24 tokens, random seed 42, prompt saving enabled, and resumable runs enabled. |
| Quantisation settings | BF16 reference plus GPTQ-8, GPTQ-4, and AWQ-4. Quantised runs use group size 128, asymmetric zero-point quantisation where supported, and source precision for embeddings and the language-model head. |
| Calibration | Balanced English–German–Bavarian calibration condition, seed 42, target size approximately 250k tokens, and calibration sequence length 2048. No exact normalised-text overlap was detected with BavGround questions, answer options, or recorded source references. |
| Runtime telemetry | Run metadata records model-loading duration, peak allocated and reserved GPU memory after loading and inference, average and maximum power draw, total energy, phase-level energy for model loading and inference, and nvidia-smi snapshots before and after execution. |
| Parameter | Main-matrix setting |
|---|---|
| GPTQ weight precision | 8-bit or 4-bit |
| AWQ weight precision | 4-bit |
| Group size | 128 |
| Calibration budget | 250k tokens |
| Calibration sequence length | 2048 |
| Calibration seed | 42 |
LLM Quantization
Large language model quantization reduces numerical precision to lower memory use and accelerate training or inference.
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