{ "background": "The persistent productivity gap in the manufacturing sector necessitates robust methods for evaluating systemic interventions. Existing approaches for assessing plant-wide efficiency gains often lack rigorous counterfactual analysis, limiting causal inference in complex industrial settings.", "purpose and objectives": "This paper develops and presents a methodological framework for the quasi-experimental evaluation of integrated systems interventions within manufacturing plants. The objective is to provide a structured, replicable approach for estimating causal effects on technical efficiency.", "methodology": "The framework employs a difference-in-differences design, leveraging phased implementation across production lines. The core econometric model is $Y{it} = \\beta0 + \\beta1 (Treati \\times Postt) + \\gamma X{it} + \\alphai + \\deltat + \\epsilon{it}$, where $Y{it}$ is a composite efficiency score. Inference is based on cluster-robust standard errors at the production-line level to account for serial correlation.", "findings": "As a working paper, this article presents the framework and its theoretical underpinnings but does not contain final empirical results. A pilot application indicated a preliminary positive direction for the treatment effect, with the point estimate suggesting an efficiency gain in the range of 8-12%. The methodological exercise highlighted critical themes, including the importance of baseline parallel trends and the handling of spillover effects.", "conclusion": "The proposed framework offers a viable and rigorous alternative to conventional before-after comparisons for engineering systems evaluation. It formally addresses key threats to validity, such as secular trends and time-varying confounders, common in plant environments.", "recommendations": "Practitioners applying this method should conduct pre-intervention parallel trends tests and consider propensity score matching for the initial assignment of treatment phases. Future empirical work should collect high-frequency operational data to enhance the model's granularity.", "key words": "quasi-experimental design, difference-in-differences, manufacturing systems, efficiency measurement, causal inference, industrial engineering", "contribution statement