Joint Modeling of Access to Improved Water and Sanitation in Nigeria: A Copula-Based Generalized Joint Regression and Spatial Semiparametric Approach
DOI:
https://doi.org/10.62054/ijdm/0303.23Abstract
This study investigates the joint determinants of access to improved water and sanitation facilities in Nigeria, accounting for dependence, nonlinear effects, and spatial heterogeneity. The analysis is based on data from the 2024 Nigeria Demographic and Health Survey (NDHS). A copula-based Generalized Joint Regression Model (GJRM) was employed to model water and sanitation access while capturing their interdependence. The results reveal a significant positive dependence between access to improved water and sanitation in the baseline model, indicating that households with access to one service are more likely to have access to the other. Socio-economic variables such as household wealth and urban residence were found to be strong predictors, with households in the richest quintile having over 3 times higher likelihood of accessing both services compared to the poorest quintile. Nonlinear effects were observed for household size and age. Spatial analysis further revealed pronounced regional disparities, with significantly higher access levels in southern regions compared to northern regions. Sanitation access exhibited stronger spatial clustering than water access, highlighting localized inequalities in infrastructure distribution. Overall, the study demonstrates that access to water and sanitation in Nigeria is shaped by a complex interplay of socio-economic, demographic, and spatial factors.
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