Brazil demographic study evaluates municipal population projection uncertainty

A study analyzing the 2022 Brazilian Demographic Census highlights an advanced stage of demographic transition in Brazil, marked by declining fertility, changing age structures, and decelerating population growth. Between 2010 and 2022, many municipalities saw significant growth attenuation or even population decline.

Researchers evaluated the predictive accuracy of the AiBi method, which is commonly used for subnational population projections in Brazil. By integrating a Random Walk with Drift method with AiBi’s point projections, the study quantified uncertainty in municipal projections by sex across the states of Rio Grande do Norte and São Paulo.

The findings indicate that projection uncertainty is influenced by population size, the stability of historical trends, and the length of the forecast horizon. Uncertainty intervals were found to widen in smaller municipalities, areas with volatile growth patterns, and as the forecast period extends.