What do we mean by Global South? Evidence of a construct validity problem.

This letter to the editor of Scientometrics examines the construct validity problem affecting the concept of 'Global South' in the bibliometric literature: more than 62% of the 14,631 articles indexed in Web of Science (1975-2024) that use the term do not explicitly define it. The authors identify three distinct analytical logics — material/economic, epistemic/relational, and historical-colonial — that produce divergent country sets, generating incompatible results in borderline cases such as BRICS or Gulf economies. In response, they propose a situational classification framework that turns the choice of demarcation criterion into an explicit and comparable analytical decision, and suggest considering the centre/periphery pair as a more rigorous relational alternative for evaluative bibliometrics. The full classification framework is developed in detail in a companion manuscript, available at DOI: 10.5281/ZENODO.20643688.