arXiv Machine Learning By Lalchand Pandia, Kanishka Misra, Allyson Ettinger

Rethinking Data Selection: The Importance of Coverage over Difficulty in LLM Fine-Tuning

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The paper argues that for fine‑tuning large language models, selecting training data based on coverage of the input space is more effective than selecting based on difficulty. While difficulty‑based scores work for smaller classification models, they often underperform random sampling for LLMs. The authors propose a simple clustering‑based method that improves coverage and achieves performance equal to or better than random selection, especially on multi‑domain tasks.

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