## 4 Application
### DEA-Based PROMETHE II Model Development  
For this study, seven equally weighted criteria were employed in order to develop the proposed PROMETHEE II-DEA model. These criteria are listed and briefly described as follows:  
* Vehicle Off Road (VOR) The terminology Vehicle Off Road is commonly utilized to label idle vehicles that are in the process of repair due to the unavailability of certain parts, which consequently leads to an increase in the waiting time, and eventually, increases the number of dissatisfied customers. The VOR rate can be calculated as the number of VOR orders divided by the total number of orders as shown below.
* Number of Employees (NE) This criterion is limited to the actual NE dedicated directly to certain critical aspects and functions inside the distribution center.
* Stock Efficiency (SE) This criterion measures the extent to which a certain distribution center is operationally healthy by considering only the moving amount of stock. This can be measured by dividing the total stock value, excluding the value of the over-stock as well as the value of the non-moving items, by the total stock value as shown below.
* Stock Month (SM) This criterion aims to identify to what extent a certain distribution center is capable of covering the monthly demand (units on a monthly basis). This can be measured by dividing the on-hand stock quantity by the monthly demand quantity as shown below.
* Immediate Supply Job Card Fill Rate (JCFR) Task Achievement This criterion is calculated by dividing the total number of job cards fully supplied from the shelves (stock) by the total job cards received/opened by the spare parts department on a daily basis as follows.
* Service Rate (SR) This criterion can be measured by dividing the total number of customer orders fulfilled completely (closed) by the total number of customer orders.
* Guest Delight Index (GDI) The guest delight index is a critical indicator that is usually prepared by the Customer Care Management Department. The GDI measures the customer satisfaction level through a daily feeding mechanism in each service/distribution center using different approaches such as direct phone calls, hard copy questionnaires, or electronic questionnaires.  
The PROMETHEE II model developed herein was constructed to rank nine DCs considering the abovementioned criteria. Two criteria are considered as cost criteria in the sense that having lower values with respect to these criteria will be reflected in a better rank for the DC under assessment. These cost criteria include the NE and the VOR ratio. The remaining five criteria are considered as benefit criteria in the sense that having higher values with respect to these criteria will be reflected in a better rank for the DC under assessment. These criteria include SE, SM, SR, JCFR, and GDI.  
Regarding the developed DEA model, the model was formulated in order to measure the efficiency of the nine DCs considering the same criteria. The purpose behind the employment of the DEA model is to examine each DC in order to determine the extent to which it can record or achieve maximum SE, SM, SR, JCFR, and GDI through utilizing a minimum NE and keeping the VOR ratio to the minimum as much as it can be. Consequently, the input measures for the developed output-oriented DEA model include the NE and the VOR ratio, while the remaining five criteria (SE, SM, SR, JCFR, and GDI) are considered as output measures. The collected data are presented in Table 1.