Читать книгу Intermittent Demand Forecasting - John E. Boylan - Страница 89

At what levels should service level targets be set? This is not an easy question to answer. Nevertheless, if an organisation is clear on the priority level of inventory service as part of its positioning, and the costs it is prepared to bear, then it is in a good position to set service level targets strategically.

An assessment of service level options should be informed by an evaluation of the trade‐off between service level and cost. It is here that well‐designed inventory systems can be very helpful. An early example was given by Johnston (1980), who designed an interactive stock control system for builders' merchants. He included a facility to allow managers to experiment with alternative stocking strategies, using the system to provide estimates of the anticipated average stock values, stock turns, service levels, and expected lost sales per annum. This type of analysis can enable exchange curves to be drawn, such as that illustrated in Figure 3.2.

Figure 3.2 shows an example of the trade‐off between fill rates and average inventory values. Curves such as this can be drawn for whole categories of stocks for which different service level targets may be applied. For example, separate analyses could be conducted for fast, medium, and slow‐moving SKUs and service level targets set accordingly for each stock category.

Exchange curves can be drawn only if the inventory system allows the simulation of inventories with different service level targets. At a higher strategic level, it is possible to design systems to allow experimentation on service level targets at a stocking location, or to examine the stock implications of merging two stocking points (Johnston et al. 1988).

Figure 3.2 Exchange curve.