Longitudinal Analysis of the Impact of Design Policy Interventions on Nigerian SME Innovation Performance

The relationship between design policy interventions and innovation performance in small and medium enterprises has been extensively studied in European contexts but remains theoretically and empirically underdeveloped in Sub-Saharan Africa. This doctoral study conducts a longitudinal analysis of the impact of design policy interventions on innovation performance among Nigerian SMEs over a ten-year period, contributing an original empirical evidence base and theoretical model applicable to design policy evaluation in developing economies. Drawing on innovation policy theory, design economics, and institutional economics, the research combines a panel dataset constructed from National Bureau of Statistics SME surveys supplemented by proprietary design support programme records, in-depth longitudinal case studies of twelve SMEs tracked over five years, and policy document analysis of design-relevant provisions across successive Nigerian government industrial and innovation policies. Difference-in-differences estimation is applied to evaluate the causal impact of participation in design support programmes on innovation output indicators including new product introductions, process improvements, export market entry, and intellectual property registration. Findings reveal significant positive impacts for SMEs receiving intensive design mentoring and prototype development support, with effect sizes substantially larger than those associated with training-only or information-only interventions. The study introduces the Design Policy Impact Chain Model, specifying the mediating mechanisms through which policy inputs translate into SME innovation outcomes in the Nigerian context, and identifies the institutional complementarities required for these mechanisms to operate effectively. Recommendations provide evidence-based guidance for the Industrial Training Fund and Bank of Industry design support programme design. Keywords: design policy, SME innovation, longitudinal analysis, Nigeria, design economics.