The fabric of movement: linking patterns, drivers, and mechanisms in international migration

Thesis

International migration exhibits persistent empirical regularities in how movement is organised in space and time. These regularities—the spatial distribution of flows, their concentration or dispersion, the reciprocity of exchanges—can be understood as migration structures: aggregate manifestations of underlying drivers and mechanisms. Yet, migration research has rarely treated migration structures as analytically meaningful objects. Driver-oriented research has focused on which factors determine migration volumes; pattern-oriented research on how flows are distributed across space. The two literatures rarely intersect, and existing methods offer few tools to connect them.

This thesis argues that migration structure is an essential component of any complete account of human mobility. Across three empirical chapters, it develops the conceptual and methodological apparatus required to study it. The first chapter introduces Hill profiles to examine changes in the diversity of global migration from 1960 to 2020. It shows that the globalisation of international migration proceeded throughtwoindependentprocesses—corridorexpansionand flow redistribution—that operated at different historical moments, reconciling contradictory findings in the literature. The second chapter asks whether established migration theories can account for observed migration structures. Developing a simulation-based framework and applying it to intra-European migration flows, it demonstrates that theories achieving high explanatory power may nonetheless fail to reproduce key spatial features of the migration system. The third chapter challenges a foundational assumption in quantitative migration models: the independence of migration decisions. Using a statistical network model applied to European student mobility, it shows that interdependence organises movement beyond what standard predictors explain and that omitting it distorts inference about those predictors.

Taken together, the three chapters make a cumulative case: international migration has structure, structure is empirically tractable, and explaining it requires tools that standard approaches do not provide. This thesis seeks to lay the groundwork for such an agenda.

Authors: Morellini, MM

• DOI: 10.5287/ora-7rbeoy2ba
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: migration modelling; computational sociology; migration theory; social networks; spatial demography
• Subjects: Demography--Methodology; Applied human geography; Population; Human geography; Demography--Statistical methods; Sociology; Demography; Migration