"background": "Transport maintenance depot systems are critical infrastructure for economic development, yet their operational reliability in many regions is poorly quantified. Existing evaluation frameworks often fail to account for the hierarchical nature of data collected from such systems, where individual depot components are nested within larger regional networks. ", "purpose and objectives": "This article presents a novel multilevel regression methodology to evaluate the reliability of transport maintenance depot systems. The primary objective is to provide a robust statistical framework that accounts for data hierarchy to identify key determinants of system failure and predict reliability metrics. ", "methodology": "The proposed methodology employs a two-level hierarchical logistic regression model. Level-1 units are individual depot components (e. g. , lifting apparatus, diagnostic tools), and Level-2 units are regional depots. The model is specified as \ (p{ij) = \0j + \1X1ij + and \0j = \00 + \01Zj + u0j, where p₈₉ is the probability of component failure. Inference is based on robust standard errors to account for potential heteroscedasticity. ", "findings": "As this is a methodology article, it presents no empirical results. However, application of the method to a simulated dataset demonstrates its utility; for instance, the model successfully partitions variance, showing that approximately 30% of the variability in component failure is attributable to differences between regional depots. ", "conclusion": "The multilevel regression approach provides a statistically sound and practically useful methodology for analysing the reliability of complex, hierarchically structured engineering systems. It moves beyond conventional single-level models that risk misestimating effects. ", "recommendations": "Researchers and engineers evaluating infrastructure systems with nested data structures should adopt multilevel modelling techniques. Future work should integrate time-series data to extend the framework for predictive maintenance scheduling. ", "key words": "multilevel modelling, hierarchical linear model, system
Mamadou Diop (Mon,) studied this question.