Methodological Evaluation and Reliability Assessment of Industrial Machinery Fleets in Kenya: A Difference-in-Differences Modelling Approach

"background": "Industrial machinery fleets are critical for economic productivity, yet systematic methodologies for evaluating their operational reliability in developing economies are lacking. Existing approaches often fail to account for unobserved heterogeneity and external shocks, leading to imprecise assessments of system performance. ", "purpose and objectives": "This study aims to develop and apply a robust econometric framework to methodologically evaluate the reliability of industrial machinery fleets. The primary objective is to quantify the causal effect of a major national maintenance protocol intervention on fleet operational availability. ", "methodology": "A quasi-experimental difference-in-differences (DiD) model was employed, analysing panel data from 87 machinery fleets. The core specification is Y{it = \ + \ (Treatmenti \ Postt) + \ + \ +, where Y₈ₓ is the operational availability rate. Inference is based on cluster-robust standard errors at the fleet level. ", "findings": "The intervention significantly increased average operational availability by 7. 3 percentage points (95% CI: 5. 1 to 9. 5). The parallel trends assumption was validated, and the result was robust to multiple sensitivity checks, including a placebo test. ", "conclusion": "The DiD modelling approach provides a rigorous methodological framework for reliability assessment in industrial engineering contexts, successfully isolating the causal impact of a systemic intervention from confounding temporal and organisational factors. ", "recommendations": "Adoption of the DiD methodology is recommended for asset management policy evaluation. Industrial operators should implement structured panel data collection to facilitate such causal analyses for informed maintenance strategy decisions. ", "key words": "reliability engineering, difference-in-differences, machinery fleets, maintenance policy, causal inference, operational availability", "contribution statement": "This paper provides the first application of a quasi-experimental difference-in-differences model to isolate the causal effect of a maintenance policy on industrial machinery fleet reliability in a sub-Saharan African context,