Comparing Without Saying: A Dataset and Benchmark for Implicit Comparative Opinion Mining from Same-User Reviews
Thanh-Lam T. Nguyen, Ngoc-Quang Le, Quoc-Trung Phu, Thi-Phuong Le, Ngoc-Huyen Pham, Phuong-Nguyen Nguyen, Hoang-Quynh Le
TL;DR
This work tackles implicit comparative opinion mining by introducing SUDO, a bi-level annotated dataset of same-user beer reviews capturing aspect mentions and per-aspect comparative preferences. It combines a two-stage annotation pipeline with rigorous data filtering and a user-level train/validation/test split to enable robust evaluation. Through comprehensive benchmarks, traditional ML baselines underperform compared with end-to-end language-model baselines, though overall accuracy remains moderate due to implicit reasoning and cross-aspect interactions. By providing a large, publicly available benchmark focused on implicit comparisons, the paper highlights key challenges and motivates future work in joint learning and cross-domain expansion.
Abstract
Existing studies on comparative opinion mining have mainly focused on explicit comparative expressions, which are uncommon in real-world reviews. This leaves implicit comparisons - here users express preferences across separate reviews - largely underexplored. We introduce SUDO, a novel dataset for implicit comparative opinion mining from same-user reviews, allowing reliable inference of user preferences even without explicit comparative cues. SUDO comprises 4,150 annotated review pairs (15,191 sentences) with a bi-level structure capturing aspect-level mentions and review-level preferences. We benchmark this task using two baseline architectures: traditional machine learning- and language model-based baselines. Experimental results show that while the latter outperforms the former, overall performance remains moderate, revealing the inherent difficulty of the task and establishing SUDO as a challenging and valuable benchmark for future research.
