{ "background": "Power-distribution losses remain a critical challenge for grid stability and economic viability in many developing nations. This case study addresses the need for robust, quasi-experimental methods to evaluate the impact of large-scale infrastructure upgrades on technical efficiency within such contexts.", "purpose and objectives": "This methodological evaluation aims to demonstrate the application of a difference-in-differences (DiD) model to quantify efficiency gains from a national programme of advanced distribution equipment deployment. The objective is to provide a replicable framework for isolating the causal effect of such interventions from confounding temporal trends.", "methodology": "A longitudinal case study design is employed, analysing panel data from treated and control regions. The core statistical model is a two-way fixed effects DiD specification: $Y{it} = \\beta0 + \\beta1 (\\text{Treated}i \\times \\text{Post}t) + \\alphai + \\gammat + \\epsilon{it}$, where $Y{it}$ is the technical loss rate. Inference is based on cluster-robust standard errors at the regional level.", "findings": "The analysis indicates a statistically significant reduction in technical losses attributable to the equipment upgrades. The DiD estimator, $\\beta1$, is -2.8 percentage points (95% CI: -4.1, -1.5), suggesting the programme substantially improved network efficiency. The parallel trends assumption, tested via event-study analysis, holds for the pre-intervention period.", "conclusion": "The DiD approach provides a rigorous methodological framework for evaluating power-distribution efficiency projects, effectively controlling for unobserved time-invariant heterogeneity and common temporal shocks. This case confirms the model's utility in an engineering-economic context.", "recommendations": "Future infrastructure evaluations should adopt quasi-experimental designs like DiD to strengthen causal claims. Utilities should implement staggered roll-outs of major projects to facilitate such analyses. Data collection protocols must ensure consistent measurement across treatment and control groups.", "key words": "difference