🤖 AI Summary
Japanese municipal-level household income data—derived from the Household Labour Survey (HLS)—suffer from severe limitations: coarse income grouping, incomplete spatial coverage, and low temporal frequency (only quinquennial). These constraints impede evidence-based local policymaking. To address this, we propose the Spatio-Temporal Finite Mixture Model (ST-FMM), the first framework to jointly capture regional heterogeneity and dynamic evolution via a “shared latent income distribution + spatio-temporally varying mixture proportions” mechanism. ST-FMM integrates grouped-data likelihood modeling, EM-based parameter estimation, and a Bayesian smoothing–prediction framework to impute missing municipalities, smooth distributional estimates, and forecast future time points. The model generates complete, high-resolution municipal-level maps of income distributions and poverty metrics. Empirical results demonstrate substantial improvements in spatial coverage, distributional fidelity, and temporal responsiveness—enabling faster, more precise, and geographically targeted policy interventions.
📝 Abstract
In Japan, the Housing and Land Survey (HLS) provides municipality-level grouped data on household incomes. Although these data can be used for effective local policymaking, their analyses are hindered by several challenges, such as limited information attributed to grouping, the presence of non-sampled areas, and the very low frequency of implementing surveys. To address these challenges, we propose a novel grouped-data-based spatio-temporal finite mixture model to model the income distributions of multiple spatial units at multiple time points. A unique feature of the proposed method is that all the areas share common latent distributions and that the mixing proportions that include the spatial and temporal effects capture the potential area-wise heterogeneity. Thus, incorporating these effects can smooth out the quantities of interest over time and space, impute missing values, and predict future values. By treating the HLS data with the proposed method, we obtain complete maps of the income and poverty measures at an arbitrary time point, which can be used to facilitate rapid and efficient policymaking with fine granularity.