Improving Romanian LLM Pretraining Data using Diversity and Quality Filtering
Vlad Negoita, Mihai Masala, Traian Rebedea
TL;DR
The paper addresses the scarcity and variable quality of Romanian pretraining data for LLMs. It introduces a multidimensional filtering pipeline that uses a lightweight multitask annotator to predict educational value, topic, format, and education level, leveraging a small human-labeled set and a large LLM-labeled corpus. The authors construct FineWeb2-Edu-Ro and demonstrate that filtering improves continual pretraining performance on Romanian benchmarks (RoMMLU, RoARC, RoHellaSwag) and reveals cross-lingual differences in topic distributions. They also discuss limitations related to data size under scaling laws and limited format diversity, proposing future work to broaden data diversity and coverage across formats and domains.
Abstract
Large Language Models (LLMs) have recently exploded in popularity, often matching or outperforming human abilities on many tasks. One of the key factors in training LLMs is the availability and curation of high-quality data. Data quality is especially crucial for under-represented languages, where high-quality corpora are scarce. In this work we study the characteristics and coverage of Romanian pretraining corpora and we examine how they differ from English data. By training a lightweight multitask model on carefully LLM-annotated Romanian texts, we are able to analyze and perform multi-level filtering (e.g., educational value, topic, format) to generate high-quality pretraining datasets. Our experiments show noteworthy trends in the topics present in Romanian and English data, while also proving the effectiveness of filtering data through improved LLM pretraining performance across multiple benchmarks.
