Research map / Large language models / Alignment and preferences
Improving Model Alignment Through Collective Intelligence of Open-Source Models
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Proposes Mixture of Agents Alignment (MoAA), which uses an ensemble of open-source LLMs as a data generator for SFT and as a pairwise reward model for DPO preference labeling, improving Llama-3.1-8B-Instruct and Gemma-2-9B-it.
Problem
Human-labeled alignment data is expensive and hard to scale, and synthetic data from a single strong (often proprietary) teacher has limited diversity and reproducibility. The paper asks whether collective open-source LLMs can supply better SFT and preference data.
Approach
Apply the Mixture-of-Agents (proposer/aggregator layered) architecture to generate SFT responses and to act as a pairwise reward model (with order-swapped evaluation and dynamically selected criteria) for labeling DPO preference pairs, so that the aligned model can match or exceed the MoA teacher and self-improve.
Key results
- Llama-3.1-8B-Instruct AlpacaEval 2 LC win rate rises from 22.33 to 57.23 and Arena-Hard from 19.5 to 48.3 after MoAA-SFT followed by MoAA-DPO.
- Gemma-2-9B-it-MoAA-DPO reaches 63.75 AlpacaEval 2 LC and 55.6 Arena-Hard, exceeding its base (47.43 / 42.0).
- Gemma-2-9B-it-MoAA-DPO achieves 90.6% of MoA performance at roughly 5.4% of its inference cost.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Apply MoAA-SFT to Llama-3.1-8B-Instruct | Llama-3.1-8B-Instruct · AlpacaEval 2 (LC) | win rate: 22.33 -> 43.77 | Helped |
| Apply MoAA-DPO after MoAA-SFT | Llama-3.1-8B-Instruct · AlpacaEval 2 (LC) | win rate: 43.77 -> 57.23 | Helped |
| Apply MoAA-SFT to Gemma-2-9B-it | Gemma-2-9B-it · Arena-Hard | win rate: 42.0 -> 47.6 | Helped |
| Apply MoAA-DPO after MoAA-SFT | Gemma-2-9B-it · MT-Bench | score: 8.65 -> 8.91 | Helped |
| Use MoA-generated SFT data instead of Best of 5 teacher data (ablation) | Llama-3.1-8B-Instruct SFT · AlpacaEval 2 (LC) | win rate: 35.62 -> 43.77 | Helped |
| Use MoA-generated SFT data instead of Combined 5 data (ablation) | Llama-3.1-8B-Instruct SFT · Arena-Hard | win rate: 26.7 -> 40.8 | Helped |
| Use MoA-generated SFT data instead of Random 5 data (ablation) | Llama-3.1-8B-Instruct SFT · MT-Bench | score: 8.19 -> 8.33 | Helped |
| Combine Ultrafeedback with 5,000 Ultrachat examples for SFT data (ablation) | Llama-3.1-8B-Instruct MoAA-SFT · AlpacaEval 2 (LC) | win rate: 39.92 -> 43.77; 43.86 -> 43.77 | Mixed |
| Use Ultrachat rather than UF + UC for SFT data (ablation) | Llama-3.1-8B-Instruct MoAA-SFT · MT-Bench | score: 8.33 -> 8.39 | Helped |
| Add criteria filtering to the MoA reward model (ablation) | MoA reward model · RewardBench Average | score: 84.5 -> 85.6 | Helped |
| Add criteria filtering to the MoA reward model (ablation) | MoA reward model · RewardBench Chat | score: 95.5 -> 94.7 | Hurt |
| Fine-tune the strongest MoA member, Gemma-2-9B-it, on MoA-generated data (ablation) | Gemma-2-9B-it · AlpacaEval 2 (LC) | win rate: 58.62 -> 54.19 | Hurt |
Surprising findings
- SFT on a small-scale MoA mixture let Gemma-2-9B-it outperform the strongest individual model in its own mixture, suggesting self-improvement beyond teachers.
- Naive combination of multi-model data (Combined 5, Random 5) underperformed single-model-generated synthetic data from GPT-4o in some settings, and MoA as reward model scored lower than ArmoRM on RewardBench yet produced a better DPO model on MT-Bench and Arena-Hard.
Limitations
- Architecture selection was done by manual/empirical search and an early BFGS attempt; no principled optimization of the mixture.
- Multi-turn synthetic data may suffer discontinuity; model-judge reward relies on GPT-4-based benchmarks that may be biased toward GPT-4 style.
- Benchmarks (AlpacaEval 2, Arena-Hard, MT-Bench) are judged by GPT-4 variants, and reasoning ability showed slight drops after MoAA-SFT for Llama.
Experimental setup
Datasets: UltraFeedback UltraChat-200k RewardBench PPE AlpacaEval 2 Arena-Hard MT-Bench MMLU HumanEval GPQA MATH
Benchmarks: AlpacaEval 2 Arena-Hard MT-Bench RewardBench PPE MMLU HumanEval GPQA MATH
Metrics: length-controlled win rate win rate MT-Bench score accuracy pass@1
Baselines: Combined 5 Random 5 Best of 5 (ArmoRM-Llama3-8B-v0.1) MAGPIE-Pro Meta-Rewarding LM GPT-4o-2024-05-13 data PairRM ArmoRM-Llama3-8B-v0.1 Llama-3.1-70B-Instruct as reward model Qwen2-72B-Instruct as reward model Gemma-2-27B-it as reward model
Builds on: Mixture of Agents DPO Magpie Meta-Rewarding LLM
Closest papers by meaning
- Mixture-of-Agents Enhances Large Language Model Capabilities (ICLR 2025 · similarity 0.91)
- Aligner: Efficient Alignment by Learning to Correct (NeurIPS 2024 · similarity 0.90)
- Collab: Controlled Decoding using Mixture of Agents for LLM Alignment (ICLR 2025 · similarity 0.89)
- Magpie: Alignment Data Synthesis from Scratch by Prompting Aligned LLMs with Nothing (ICLR 2025 · similarity 0.89)
- The Unlocking Spell on Base LLMs: Rethinking Alignment via In-Context Learning (ICLR 2024 · similarity 0.88)
- Learn Your Reference Model for Real Good Alignment (ICLR 2025 · similarity 0.88)
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