Crowd-Sourced Geographies of Income: Using Google Maps Points of Interest as High-Frequency Proxies for Sub-Municipal Income Estimation in Sao Paulo, Brazil
This study addresses the scarcity of high-frequency, low-cost sub-municipal income data in middle-income countries between censuses, which hampers effective social policy design. It presents the first systematic validation of Google Maps points of interest (POIs) as a high-frequency proxy for household income at the census tract level across São Paulo, covering 26,625 areas. The authors reduce the dimensionality of sparse POI features using principal component analysis (PCA) and non-negative matrix factorization (NMF), then integrate these with gradient boosting regression models. Employing spatially aware cross-validation to prevent data leakage, the optimal NMF-enhanced gradient boosting model achieves an R² of 0.65, demonstrating robust predictive performance. The analysis further identifies specific POI categories significantly associated with income, offering a novel paradigm for fine-grained socioeconomic monitoring.