Abstract
Population-normalized indicators (e.g., GDP per capita), under the assumption of the indicators scaling linearly with population, are ubiquitously used in national development performance comparison. This assumption, however, is not valid because it may ignore agglomeration effect resulting from nonlinear interactions in socioeconomic systems. Here, we present extensive empirical evidence showing the sub-linear scaling rather than the presumed linear scaling between population and multiple indicators of national development performance. We then develop a theoretical framework based on the scaling rule observed in cities to explore the origin of scaling in countries. Finally, we demonstrate that urbanization plays a pivotal role in transforming national development from limited sub-linear growth to unlimited super-linear growth. This underscores the significance of urbanization in achieving sustained growth and elevating human living standards at the national level. Our findings have the potential to inform policies aimed at promoting equitable inter-country comparison and achieving sustainable development in countries.