cs.CLOct 27, 2025

Reclaiming Low-Quality Instruction Data with Rule-Guided LLM Reconstruction

Authors: Zile Yang, Ling Li, Na Di, Jinlong Pang, Yao Zhou, Hao Cheng, Bo Han, Jiaheng Wei

Organizations: The Hong Kong University of Science and Technology (Guangzhou) · University of California, Santa Cruz · Hong Kong Baptist University

Abstract

Data selection for supervised fine-tuning (SFT) often discards low-scoring instruction examples that may retain useful supervision. We propose a rule-guided LLM reconstruction framework to reclaim this information. The framework identifies low-scoring samples through LLM-based rating and score correction, selects semantically representative sources, and reconstructs instruction-response pairs through strategy-guided generation, criteria-based validation, and failure-guided repair. From 123,786 low-scoring samples, it constructs 54,888 training examples. Across three 7B/8B base LLMs, the reconstructed data achieves higher average downstream performance than the low-scoring source set and all evaluated data-selection baselines. Despite using substantially fewer examples than the full source dataset (approximately 300K), it achieves higher reported average scores than full-data training across all three base models. Stepwise ablations identify rule-guided reconstruction as the largest source of observed improvements over direct fusion, while a manual audit reveals remaining limitations in source integration and answer faithfulness. These findings support reconstruction as a complementary approach to selection-based SFT data curation.

Figures & tables

Appendix figures & tables41 assets

Supplementary material from the paper’s appendix.

Appendix

Explore similar work

CardsList
  1. A Critical Look at Targeted Instruction Selection: Disentangling What Matters (and What Doesn't)

    Feb 16, 2026Nihal V. Nayak, Paula Rodriguez-Diaz, Neha Hulkund +2Instruction-Tuning Data SelectionTraining Data Selection

  2. From Instance Selection to Fixed-Pool Data Recipe Search for Supervised Fine-Tuning

    May 13, 2026Haodong Wu, Jiahao Zhang, Lijie Hu +1Supervised Fine-TuningTraining Data Curation

  3. FineInstructions: Scaling Synthetic Instructions to Pre-Training Scale

    Jan 29, 2026Ajay Patel, Colin Raffel, Chris Callison-BurchLanguage Model PretrainingSynthetic Data Pretraining