Out-of-Distribution Detection on Graphs: A Survey
Tingyi Cai, Yunliang Jiang, Yixin Liu, Ming Li, Changqin Huang, Shirui Pan
TL;DR
This survey formalizes graph out-of-distribution (GOOD) detection, defining IND vs. OOD graphs and presenting a four-way taxonomy of approaches. It comprehensively reviews enhancement-, reconstruction-, information propagation-, and classification-based methods, with representative techniques and notable examples such as VGAE-based reconstructions, energy/uncertainty propagation, and boundary-focused classifiers. The work also maps common node- and graph-level datasets, cross-domain OOD splits, and standard benchmarks like DrugOOD and UB-GOLD, while discussing practical applications, theoretical underpinnings, and future directions. By clarifying distinctions from graph anomaly/outlier detection and GOOD generalization, the paper lays a foundation for scalable, explainable, and robust graph learning under distribution shifts, and highlights promising directions such as graph foundation models with OOD awareness.
Abstract
Graph machine learning has witnessed rapid growth, driving advancements across diverse domains. However, the in-distribution assumption, where training and testing data share the same distribution, often breaks in real-world scenarios, leading to degraded model performance under distribution shifts. This challenge has catalyzed interest in graph out-of-distribution (GOOD) detection, which focuses on identifying graph data that deviates from the distribution seen during training, thereby enhancing model robustness. In this paper, we provide a rigorous definition of GOOD detection and systematically categorize existing methods into four types: enhancement-based, reconstruction-based, information propagation-based, and classification-based approaches. We analyze the principles and mechanisms of each approach and clarify the distinctions between GOOD detection and related fields, such as graph anomaly detection, outlier detection, and GOOD generalization. Beyond methodology, we discuss practical applications and theoretical foundations, highlighting the unique challenges posed by graph data. Finally, we discuss the primary challenges and propose future directions to advance this emerging field. The repository of this survey is available at https://github.com/ca1man-2022/Awesome-GOOD-Detection.
