Cities with a wide variety of unrelated industries were actually more fragile during the COVID-19 pandemic.
Economic wisdom has always suggested that a diverse portfolio of businesses protects a city from shocks. This study shows that true resilience comes from related diversity, where different businesses share similar skills or supply chains. When a crisis hits, workers and resources can move between similar industries but cannot easily jump from retail to high-tech manufacturing. A city full of completely different sectors ends up with isolated pockets of failure that cannot help one another. Real-world stability depends on how well a city's various parts can actually talk to each other.
Related diversification, not generic breadth: industrial composition and urban resilience to the COVID-19 shock
SocArXiv · 7hfyr_v2
Industrial diversity is widely held to buffer urban economies against economic shocks, yet evidence remains mixed and the operative mechanisms poorly understood. Using establishment-count data for 131 wards across nine Japanese designated cities and Tokyo (2016--2021), we apply Bayesian spatial error models to examine how three diversity dimensions---within-ward breadth ($\alpha$-diversity), between-ward compositional heterogeneity ($\beta$-diversity), and related/unrelated variety---independent