"background": "Power-distribution systems in many developing nations face chronic inefficiencies, leading to substantial technical and commercial losses. Evaluating the impact of equipment upgrades and interventions is complex due to hierarchical data structures and confounding regional factors. ", "purpose and objectives": "This case study presents a methodological framework for quantifying efficiency gains in power-distribution networks. It aims to demonstrate the application of multilevel regression modelling to isolate the effect of equipment modernisation from other operational variables. ", "methodology": "A longitudinal dataset from a national utility was analysed using a three-level mixed-effects model. The core statistical model is y{ij = \0 + \1Xij + uj + vk +, where yij is system efficiency for feeder i in region j, Xij denotes intervention status, and uj, vₖ are random intercepts for region and year, respectively. Inference was based on robust standard errors. ", "findings": "The analysis indicates a statistically significant positive association between modernised equipment deployment and network efficiency. A key concrete result is that feeders with fully modernised equipment showed, on average, a 7. 2 percentage-point increase in efficiency (95% CI: 5. 1 to 9. 3) compared to the baseline, controlling for regional heterogeneity and load growth. ", "conclusion": "The multilevel regression approach provides a robust analytical tool for infrastructure investment appraisal in the power sector, effectively accounting for clustered data. It offers a more nuanced understanding of intervention efficacy than aggregate analysis. ", "recommendations": "Utilities should adopt hierarchical modelling for post-implementation reviews of capital projects. Regulatory bodies should consider such methodologies when setting performance benchmarks and evaluating tariff adjustments linked to efficiency improvements. ", "key words": "multilevel modelling, power distribution, technical losses, infrastructure evaluation, statistical analysis, developing economies", "contribution statement": "This study provides a novel methodological framework for the engineering evaluation of
Ocen et al. (Sun,) studied this question.