Empirical Analysis of the Influence of Procurement Delivery Method on Infrastructure Cost Performance in North Central Nigeria

Infrastructure project cost performance in North Central Nigeria varies significantly across procurement delivery methods, but empirical quantification of these differences using a Nigerian-specific project data set is absent from the literature. This study empirically analyses the influence of procurement delivery method on cost performance for 45 infrastructure projects in Plateau, Benue, Niger, Kwara, Kogi, and Nasarawa States. Project data including contract type, contract value, final account value, delivery duration, and project type were compiled from state ministry of works records and consulting engineering firms. Cost performance was expressed as the ratio of final account to original contract sum. Regression analysis and analysis of variance tested the statistical significance of delivery method effects. Results indicate a statistically significant effect of delivery method on cost performance (F = 8.42, p < 0.001). Design-and-build contracts show the lowest mean cost overrun at 14 percent, compared to traditional design-bid-build at 38 percent and management contracting at 29 percent. Project size negatively moderates the delivery method effect, with very large projects showing poor performance regardless of delivery method. The study fills an empirical gap in Nigerian procurement performance literature by providing zone-specific multi-method comparison, recommending that North Central state governments consider design-and-build as the preferred delivery model for road and drainage infrastructure contracts below 2 billion naira. Keywords: procurement method, infrastructure cost performance, North Central Nigeria, design-and-build, empirical analysis