Urban hierarchy and spatial diffusion over the innovation life cycle

Author: Eszter Bokányi

For decades, spatial diffusion has been argued to take place along the urban hierarchy. Yet, the role of geographical distance was difficult to identify in hierarchical diffusion due to missing data on spreading events. We exploit spatial patterns of individual invitations sent from registered users to new users over the entire life cycle of a Hungarian social media platform. We demonstrate that hierarchical diffusion overlaps with diffusion to close distances and that these factors co-evolve over the life cycle in the settlement-level normalized invitation network, that is a directed weighted network of time-evolving outgoing invitation probabilities. We show in the figure the most probable diffusion tree in the abstract invitation network, represent the same tree over Hungarian settlements, and show the evolution of most probable edges in the distance - hierarchy dimensions.