When is a move a migration?
"This paper extends the traditional theory of urban location to derive a consistent model of inter- and intra-regional mobility. It demonstrates that the two are behaviorally distinct. Workplace and residence relocations tend to be 'substitutes' in intra-regional mobility but are 'complements' in inter-regional mobility. Previous empirical papers have neglected the theoretical foundations of intra-regional mobility. In consequence, they have made four types of analytical compromises: defined 'migration' as any change in residence location, used job changes as proxies for workplace mobility, neglected commuting distances, and used estimation techniques that do not reveal the underlying behavior."
Demography↗