The Demographic Causes of European Sub-National Population Declines

Population decline has emerged as the dominant direction of population change across European sub-national areas. Despite this, its underpinning demographic causes remain under-researched and thus largely unknown. We use annual demographic count estimate data, including births, deaths, and net-migration, to understand their contributions to sub-national population declines across Europe, in a total of 732 areas encompassing 33 countries. To this end, we apply a novel methodology involving rate decomposition, multivariate functional data analysis, and k-medoid clustering. We identify five unique causes of population decline, distinguished by nuanced longitudinal contributions from changing rates of fertility, mortality, and net-migration. We further model a multinomial logistic regression analysis to understand the association between various areal attributes and each cause of depopulation, and chart their geographic distribution