A Theoretical Framework for Integrating Volunteered Geographic Information into National Spatial Data Infrastructure in Sub-Saharan Africa: Evidence from Nigeria

National Spatial Data Infrastructure frameworks in sub-Saharan Africa were conceptualised under assumptions of centralised, government-produced spatial data, leaving unresolved theoretical and institutional questions about the integration of massive, heterogeneous, volunteered geographic information streams generated by citizens through platforms such as OpenStreetMap and social media. This dissertation develops an original theoretical framework for VGI integration into Nigeria's National Spatial Data Infrastructure, addressing a fundamental gap in both infrastructure governance theory and African GIS policy literature. Building on Actor-Network Theory, institutional economics, and information quality theoretical traditions, a conceptual framework is constructed that foregrounds trust, fitness-for-purpose, data provenance, and contributor motivation as co-determinants of effective VGI institutionalisation. Empirical evidence is generated through expert interviews with forty-two stakeholders drawn from federal and state GIS authorities, the private geospatial sector, OpenStreetMap Nigeria contributors, and international development organisations. A structured multi-criteria quality assessment of VGI data layers across six Nigerian geopolitical zones is conducted to empirically characterise fitness-for-purpose gaps. The framework is evaluated through structured validity assessment by a panel of twelve senior geospatial information management experts from five African countries. Original contributions include the VGI-NSDI Integration Maturity Model comprising five institutional development stages, and a formal quality assurance protocol adapted for resource-constrained NSDI environments. Findings have policy implications for the National Space Research and Development Agency and OGC standards bodies engaged with the African NSDI agenda. Keywords: volunteered geographic information, NSDI, theoretical framework, Nigeria, VGI integration.