{ "background": "Manufacturing systems in Ghana face persistent challenges with operational reliability, which constrains productivity and economic growth. Existing policy frameworks lack robust, evidence-based diagnostic tools to assess and improve system dependability at the plant level.", "purpose and objectives": "This policy analysis evaluates a novel randomised field trial methodology designed to measure and diagnose reliability in manufacturing systems. The objective is to determine the efficacy of this approach in generating actionable data for industrial policy formulation.", "methodology": "A randomised controlled trial was implemented across a cohort of manufacturing plants. The intervention involved a structured reliability diagnostic protocol, while control plants continued with standard operations. System failure times were modelled using a Weibull proportional hazards model, $h(t|X) = \\frac{\\beta}{\\eta} \\left( \\frac{t}{\\eta} \\right)^{\\beta-1} \\exp(X^T \\gamma)$, where $X$ represents covariates. Inference was based on robust standard errors clustered at the plant level.", "findings": "Plants receiving the diagnostic intervention demonstrated a statistically significant improvement in mean time between failures (MTBF) compared to the control group, with an estimated increase of 32% (95% CI: 18% to 46%). The primary mechanism identified was the systematic identification and mitigation of procedural, rather than purely technical, failure modes.", "conclusion": "The randomised field trial provides a rigorous, transferable methodology for assessing manufacturing system reliability, generating high-quality evidence previously absent from the policy discourse.", "recommendations": "Industrial policy should integrate structured reliability diagnostics, supported by targeted technical assistance. Funding mechanisms should incentivise the adoption of evidence-based maintenance protocols derived from such empirical evaluations.", "key words": "reliability engineering, randomised controlled trial, industrial policy, maintenance, manufacturing, Weibull analysis", "contribution statement": "This paper provides the first application of a randomised field trial to engineer reliability diagnostics in an industrial policy context, establishing a methodological benchmark for evidence-based policy in the