Recent studies in Senegal have focused on the efficiency of manufacturing plants, with a particular emphasis on cost-effectiveness. The proposed methodology will employ a Difference-in-Differences (DiD) econometric model, which compares changes over time in the cost-effectiveness metrics of manufacturing plants between treated and control groups. This model accounts for potential confounding variables through instrumental variable techniques. This article establishes the foundation for applying the DiD model to assess cost-effectiveness in Senegalese manufacturing industries, offering a methodological tool that can inform policy and practice in environmental science and development. Policy makers should consider adopting this methodology to evaluate ongoing or proposed changes in industrial systems, ensuring informed decisions based on rigorous data analysis. The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.