Demographic Characteristics and Home-Purchase Affordability in Polish Counties: A Cross-Sectional and Long-Difference Analysis

In recent decades, European countries have experienced significant demographic changes, including aging societies, a decline in the working-age population, and the growing role of net migration as a driver of population growth. These processes shape housing demand, ownership structures, and socio-spatial inequalities. Poland is a special case, with very low fertility rates, strong spatial polarization, a shortage of housing resources, and rising housing costs with significant regional variation. This article addresses a research gap regarding the role of local demographic conditions in shaping home-purchase affordability. 374 Polish counties were analyzed between 2011 and 2024, using a price-to-income index. Three econometric models were employed: two cross-sectional models (2011–2013 and 2022–2024) and a long-difference model, identifying the demographic, supply-side, and institutional determinants of affordability levels and of changes over time, using Generalized Additive Models to allow for nonlinear relationships alongside standard linear specifications. Structural population characteristics and flow processes – including migration, natural change, marriage, and divorce – significantly shape housing affordability variations. By contrast, supply-side and zoning-coverage variables show weak or ambiguous associations with affordability once spatial structure is accounted for, suggesting that unobserved institutional and supply constraints play a substantive role. The study contributes by using subnational analysis and nonlinear GAMs and by distinguishing demographic stocks from demographic processes.