GOOD: A Graph Out-of-Distribution Benchmark

TL;DR

GOOD is a comprehensive benchmark designed to evaluate graph out-of-distribution learning methods, providing diverse datasets, well-defined shifts, and baseline performance results to advance research in this emerging area.

Contribution

This work introduces the first systematic OOD benchmark for graphs, with carefully designed data splits for covariate and concept shifts, and extensive baseline evaluations.

Findings

Significant performance gaps between in-distribution and OOD settings.

Different methods exhibit varied performance trends under covariate and concept shifts.

The benchmark includes 51 dataset-model combinations with baseline results.

Abstract

Out-of-distribution (OOD) learning deals with scenarios in which training and test data follow different distributions. Although general OOD problems have been intensively studied in machine learning, graph OOD is only an emerging area of research. Currently, there lacks a systematic benchmark tailored to graph OOD method evaluation. In this work, we aim at developing an OOD benchmark, known as GOOD, for graphs specifically. We explicitly make distinctions between covariate and concept shifts and design data splits that accurately reflect different shifts. We consider both graph and node prediction tasks as there are key differences in designing shifts. Overall, GOOD contains 11 datasets with 17 domain selections. When combined with covariate, concept, and no shifts, we obtain 51 different splits. We provide performance results on 10 commonly used baseline methods with 10 random runs. This results in 510 dataset-model combinations in total. Our results show significant performance gaps between in-distribution and OOD settings. Our results also shed light on different performance trends between covariate and concept shifts by different methods. Our GOOD benchmark is a growing project and expects to expand in both quantity and variety of resources as the area develops. The GOOD benchmark can be accessed via https://github.com/divelab/GOOD/.