Rethinking the Evaluation of Alignment Methods: Insights into Diversity, Generalisation, and Safety

ACL ARR 2025 May Submission6837 Authors

Abstract:

Large language models (LLMs) require careful alignment to balance competing objectives—factuality, safety, conciseness, proactivity, and diversity. Existing studies focus on individual techniques or specific dimensions, lacking a holistic assessment of the inherent trade-offs. We propose a unified evaluation framework that compares LLM alignment methods (PPO, DPO, ORPO, KTO) across these five axes, using both in-distribution and out-of-distribution datasets. Leveraging a specialized LLM‑as‑Judge prompt, validated through human studies, we reveal that DPO and KTO excel in factual accuracy, PPO and DPO lead in safety, and PPO best balances conciseness with proactivity.
Our findings provide insights into trade-offs of common alignment methods, guiding the development of more balanced and reliable LLMs.

Paper Type: Long

Research Area: Resources and Evaluation

Research Area Keywords: alignment, generalisation, safety, LLM, evaluation

Contribution Types: Model analysis & interpretability, Reproduction study

Languages Studied: english

Submission Number: 6837