Analytical Study of the Research Gap in Demographic Methods for Small Area Population Estimation in Nigeria

Accurate small area population estimates for Local Government Areas are critical for resource allocation and service planning, yet standard demographic methods have not been systematically validated for the Nigerian sub-national data environment. This study examined the research gap in small area population estimation methods for Nigerian LGAs through systematic review and original empirical comparison. A systematic scoping review identified 22 publications from 2018 to 2024 on small area estimation in sub-Saharan Africa, of which only 4 specifically addressed Nigerian LGA-level estimation. Three small area estimation approaches were empirically compared: ratio adjustment, satellite nighttime light-based model, and composite model combining census growth rates with administrative data. Estimates were produced for 24 LGAs in Plateau, Kaduna, and Lagos States and compared against NBS official projections and community-reported population counts from 50 key informants per state. The composite model showed the highest accuracy relative to key informant benchmarks (RMSE 12.4 percent). The satellite model underperformed in rural northern LGAs due to sparse nighttime light coverage despite significant population. The study identifies three critical methodological gaps: the absence of a validated inter-censal growth rate model for northern Nigerian LGAs, lack of administrative data harmonisation that could support small area models, and absent academic-government partnership for systematic LGA population estimation. Recommendations include NBS establishing an inter-censal population estimates review board and commissioning a Nigerian small area estimation methodology study.

Keywords: small area estimation, LGA population, Nigeria, demographic methods, research gap