Formal Theory of Geospatial Data Quality and Its Implications for SDI-Enabled Evidence-Based Policy in Africa

Geospatial data quality frameworks developed within the ISO 19157 standard are operationalised almost exclusively in the context of well-resourced national mapping agencies with stable data production pipelines, and do not adequately theorise the data quality challenges and governance structures pertinent to African Spatial Data Infrastructures that integrate heterogeneous data from government, NGO, commercial, and volunteer sources. This dissertation makes an original theoretical contribution to the formal understanding of geospatial data quality by developing a Contextualised African SDI Data Quality Theory that extends ISO 19157 concepts through integration with information quality theory, data governance theory, and institutional theory. The theoretical framework is empirically grounded through a comprehensive multi-country qualitative study involving sixty-seven expert interviews with SDI managers, spatial data users, and policy analysts across Nigeria, Ghana, Kenya, South Africa, and Rwanda. A novel multi-dimensional data quality impact assessment instrument, the Policy Evidence Quality Index, is developed to measure the fitness-for-purpose of geospatial data products specifically in the context of evidence-based government policy decisions. The PEQI is validated through application to eighteen policy processes in three Nigerian federal ministries, yielding psychometric evidence of reliability, construct validity, and predictive validity against policy implementation outcome quality ratings. Original theoretical contributions include a formal conceptual model of data quality fitness-for-purpose in politically contested policy environments and the African SDI Data Quality Maturity Scale. The dissertation generates direct implications for NGDI policy, statistical standards alignment, and donor-funded geospatial investment programming. Keywords: data quality theory, SDI, policy evidence, Africa, ISO 19157.