Growth in human societies is an inherently multiscale phenomenon, emerging from socioeconomic and demographic changes across nested spatial units. Yet standard macroeconomic indicators obscure these dynamics by averaging over heterogeneity in both place and population. This talk introduces a framework based on the Price equation that decomposes aggregate growth exactly into two components: endogenous income growth and selection effects across spatial scales. These selection effects capture how residential sorting, driven by preference and opportunity, interact with the economic structure of the city to affect aggregate growth. Using population and income data from the Chicago metropolitan area (2014–2019), we show that both growth and selection are highly localized, fat-tailed, and spatially correlated. Selection, defined as the covariance between income and population change, is concentrated in a small number of places and exhibits systematic scaling across counties. Despite intense local sorting, selection effects largely cancel in the aggregate, revealing how volatile and unequal micro-dynamics can produce stable macroeconomic trends. By treating neighborhoods as evolving subpopulations under selection, this framework furthermore connects methods from complex systems to urban sociology, providing a new way to identify processes such as gentrification and abandonment. More broadly, it offers a general approach to understanding compositional change in any nested economic system, from cities to innovation and production networks.

About the speaker:

Jordan Kemp's research develops a multilevel science of human organization to understand how spatial dynamics shape inequality, economic opportunity, and demographic change across individuals, neighborhoods, and cities. Drawing on population ecology, statistical physics, information theory, and complex systems, he works to identify universal patterns in spatial sorting, growth, and redistribution that are obscured by conventional aggregation. He is interested in how local processes of demographic and economic selection accumulate into neighborhood and metropolitan change, and how cities reorganize in response to shifting labor markets, infrastructure, and macroeconomic shocks. Ultimately, his work seeks to connect individual behavior and residential dynamics with large-scale social and economic transformation, providing a mechanistic framework for understanding urban inequality in a rapidly urbanizing world. Jordan is a postdoctoral research fellow at the Santa Fe Institute and an external fellow at the Institute for New Economic Thinking at Oxford. He holds a PhD in physics from the University of Chicago, where he studied under Luís Bettencourt.

If you wish to attend this seminar online, please send an email to m.t.pham@uva.nl to receive the zoom-link.