Wholesale provisioning models : model evaluation

Abstract

Two inventory models were proposed in an earlier report to replace the current models for determining the initial range and depth of wholesale level inventories of secondary items managed by the Navy's Ships Parts Control Center (SPCC) and the Aviation Supply Office (ASO). The objectives of these models were to minimize the aggregate mean supply response time (MSRT) or to maximize the aggregate gross effectiveness (G-E) for the spare and repair parts of a new weapon system. The constraint in each model was the budget available to procure the parts. This report presents the evaluation of the proposed models using data from seven actual systems previously provisioned by SPCC and five actual systems previously provisioned by ASO. The Navy's criterion for accepting a new model was that it had to provide at least a 5% improvement over the existing models, the Variable Threshold (VT) model of SPCC and the D52 model of ASO, using aggregate mean supply response time and aggregate gross effectiveness as the performance measures. The evaluations showed that the MSRT model easily satisfied this criterion for ten of the systems and gave the same results as the existing models for the other two. The G-E model did not perform as well but did perform better than the current models for the same ten systems and gave the same results as the existing models for the other two systems. As a consequence of these evaluations, the Navy accepted the MSRT model in December of 1984. (Author)