The relative (un)certainty of subnational population decline

Abstract

“Prediction is very difficult, especially about the future.” This quote is attributed to Danish physicist and Nobel prize winner Niels Bohr, but the difficulty of making predictions does not stop us from making forecasts of economic, demographic, and other variables. Investors, businesses, policy makers and others use these forecasts to inform their decisions about investments and policy settings where understanding of the future trajectory and levels of costs and benefits are essential. One key example is forecasts of future population. The size and distribution (whether geographic, age, ethnic, or some other distribution) of the future population is a critical input into urban and other planning. Understanding the methods and limitations of forecasts is an important but often underappreciated task for planners and policymakers.