"background": "Transport depot maintenance systems in Nigeria are critical for national infrastructure but suffer from chronic inefficiencies. Current evaluations often fail to account for the hierarchical structure of depot operations, where individual maintenance tasks are nested within specific depots and regional networks. ", "purpose and objectives": "This paper aims to develop and apply a multilevel modelling framework to quantify efficiency gains within these hierarchical maintenance systems. The objective is to isolate the variance in efficiency attributable to depot-level management practices versus broader regional operational factors. ", "methodology": "A multilevel regression model was specified: y{ij = \0 + \1Xij + uj + eij, where yij is the efficiency score for task i in depot j, Xij are task-level covariates, uj are random effects for depots, and eij is the residual error. Robust standard errors were used for inference. Data were collected from maintenance logs and performance audits across a stratified sample of depots. ", "findings": "Depot-level management practices accounted for approximately 38% of the observed variance in task efficiency scores. A one-unit increase in the standardised depot management score was associated with a 0. 42 increase in task efficiency (95% CI: 0. 31 to 0. 53), holding task complexity constant. ", "conclusion": "The analysis confirms that depot-level interventions offer substantial leverage for systemic efficiency improvements, as their influence significantly outweighs that of task-specific variables within the studied hierarchy. ", "recommendations": "Investment should prioritise enhancing depot-level management capacity, including inventory control and workforce planning protocols. Future system audits should adopt hierarchical performance metrics to better target improvements. ", "key words": "multilevel modelling, infrastructure maintenance, transport engineering, efficiency analysis, hierarchical systems", "contribution statement": "This paper presents a novel application of multilevel regression to decompose efficiency variance in transport depot systems,
Suleiman et al. (Sun,) studied this question.