Appendix A Distribution Shift in Graph-Structured Data Distribution shift appears when the joint distribution differs between source domain and target domain

In all, structure shift is unique to graph data due to the non-IID nature caused by node interconnections. In this section, we provide additional details about the datasets used in our benchmark. The labels categorize airports by activity levels, measured in terms of flights or passenger numbers. Each dataset's nodes symbolize papers, while edges reflect their citation relationships. Specifically, "ACMv9" (A) includes papers from ACM spanning 2000 to 2010, "Citationv1" (C) consists of DBLP collected between 2004 and 2008.