{ "background": "Industrial process safety remains a critical challenge in many developing economies, where the adoption of advanced control systems is often inconsistent. There is a paucity of rigorous, quantitative evaluations comparing the effectiveness of different methodological approaches to process-control implementation in such contexts.", "purpose and objectives": "This study aims to empirically evaluate the comparative effectiveness of two dominant process-control system methodologies—hierarchical distributed control versus centralised supervisory control—in reducing operational risk incidents within Nigeria's industrial sector.", "methodology": "A quasi-experimental difference-in-differences (DiD) model was employed, analysing panel data from 42 industrial facilities. The core econometric specification is $Risk{it} = \\beta0 + \\beta1 (Treati \\times Postt) + \\gamma X{it} + \\alphai + \\deltat + \\epsilon_{it}$, where robust standard errors were clustered at the facility level. Treatment assignment was based on the methodology adopted.", "findings": "Facilities implementing the hierarchical distributed control methodology demonstrated a statistically significant reduction in reported risk incidents compared to the control group. The average treatment effect was an 18.2% reduction (95% CI: 12.5% to 23.9%, p < 0.01). Key themes from supplementary analysis highlighted improved fault isolation and operator response times as contributory factors.", "conclusion": "The hierarchical distributed control methodology proved more effective for operational risk reduction in the studied context than the centralised supervisory approach. This provides evidence-based guidance for system selection.", "recommendations": "Industry regulators should consider promoting the adoption of hierarchical distributed control architectures in safety-critical applications. Further research should investigate the cost-benefit analysis of system migration.", "key words": "process safety, control systems, difference-in-differences, industrial risk, Nigeria", "contribution statement": "This paper provides the first application of a quasi-experimental DiD framework to compare process-control methodologies in an industrial setting, generating causal