تاثیر ارزش فعلی خالص در ارزیابی از عملکرد پویای تجارت الکترونیکی زنجیره های تامین فعال

This paper shows the impact of using the net present value (NPV) on parameter selection in the ordering policy of a production planning and control system. Using a well understood and documented systems dynamics model of a supply chain, the NPV is used as an objective function to determine the discounted future variance costs resulting from the model's dynamics. The NPV of the Variance (NPVv) is defined and applied to the model under three scenarios; traditional, electronic-point-of-sales enabled and vendor managed inventory. It is shown that the resulting management implications are sensitive to the selection of the NPVv parameters.

E-commerce has led to potential for information transparency in the supply chain. New novel forms of supply chain structures have been enabled such as collaborative planning, forecasting and replenishment (CPFR) and vendor managed inventory (VMI). Such structures may have a positive impact on the dynamic behaviour of supply chains leading to reduced total logistics costs. Although the benefits of supply chain management (SCM) strategies are often promoted actual bottom-line cost benefits are not always cited. This may be due to the complexities associated with determining actual costs and revenues throughout an actual supply chain (Tan et al., 2002). Researchers propose alternative approaches to measuring supply chain performance, such as balanced score cards (Bullinger et al., 2002), bullwhip (Towill and McCullen, 1999), uncertainty (Childerhouse and Towill, 2002) and multivariate techniques (Tan et al., 2002; Kim and Narasimhan, 2002). But as all SCM decisions ultimately have monetary consequences research on novel and robust forms of cash flow analysis have been proposed such as Net Present Value (NPV) (Grubbström, 1999), cash-to-cash (Farris and Hutchison, 2002) and target costing (Lockamy and Smith, 2000). In this paper the NPV is investigated as a financial measure of the dynamic behaviour of supply chains. The NPV ascertains the time value of money invested in a business. Grubbström (1967) has shown that where the economic consequences of production planning decisions need to be known then the NPV may be applied. The raison d’être for this paper are: • to utilise a financial measure to assess the dynamic behaviour of supply chains, • determine the impact of NPV on parameter selection, • extend “hard engineering” know-how into the financial arena, • apply NPV via system dynamics simulation, • develop a single unified measure of performance that amalgamates a number of key dynamic characteristics. While Wikner (1994) has undertaken some analysis of applying the NPV to a systems dynamics model of a production and inventory control system, Naim et al. (2004) have shown that the standard NPV is not a sufficient criterion for analysing the dynamic behaviour of such a closed-loop form of system. There is a need to extend the NPV criterion to encapsulate costs associated with the variances that occur in the system variables. This paper describes the development of the new criterion and how it may then be applied within a supply chain context. This paper uses the automatic pipeline, inventory and order-based production control system (APIOBPCS) as a benchmark to determine the impact of using the NPV in assessing “on costs”. The APIOBPCS archetype has been shown to model decision making heuristics as given in the MIT Beer Game (Sterman, 1989) and has led to insights on the impact of information transparency (Mason-Jones and Towill, 1997). The paper next reviews literature on supply chain dynamics highlighting some recent developments on simulating the impact of information transparency as well as other SCM strategies. The paper then describes the simulation method adopted and the model used. This is followed by a presentation of the NPV formulae and its application. Next the need to use an alternative form of the NPV is justified, which is then applied to e-commerce supply chains as replicated by the MIT Beer Game. Finally, the results are discussed and managerial implications considered.

The paper has shown the impact of the net present value criterion on parameter settings for a generic production planning and control system. The analysis indicates that there is a need to develop an NPV criterion for the variance in both production and inventory costs. This new Variance NPV, or NPVv, has been applied and tested in a supply chain context using the MIT Beer Game. The literature review has highlighted the characteristics of supply chain dynamics and the need for modelling and simulation research. The MIT Beer Game has been highlighted as a classic method that may be utilised to test new supply chain performance criteria. The research indicates that care has to be taken when selecting NPVv parameter settings as the outcomes and deductions from the analysis may be sensitive to their values. There is therefore a need for further empirical research to understand what the actual variance costs structures are in industry and how they may be best evaluated. There is also a need to determine how best to develop a total cost function that may best integrate NPV and NPVv, rather than a simple addition. The results of this paper are useful for other researchers who wish to undertake further theoretical work on costing supply chain dynamics. As indicated from the literature there is a considerable gap in understanding the bottom-line implications of supply chain strategies of which e-commerce scenarios are playing an ever greater role.