Читать книгу Intermittent Demand Forecasting - John E. Boylan - Страница 56

Bartezzaghi and Verganti (1995) (see also the work by Verganti 1997; Bartezzaghi et al. 1999) proposed the order overplanning forecasting method to assist MTO manufacturers in dealing with intermittent demand. The method aims at fully exploiting early information that the prospective and regular customers generate during their purchasing process. It uses as forecasting unit each single customer order instead of the overall demand for the master production schedule (MPS) unit. So, the forecast unit is distinguished from the MPS planning unit. The expected requirements for a module (that belongs to a particular order) are overestimated. This is to take into account the sources of uncertainty within the planning horizon, namely order acquisition, actual due date, system configuration (number and types of apparatus), and apparatus configuration (modules) by implicitly incorporating in them the slack necessary to handle those uncertainties. This is done by introducing redundant configurations, so as to satisfy any request that may actually be received. The demand forecast for the MPS unit is obtained by adding up the requirements included in the individual forecast orders.

In order overplanning, forecasting is not the numerical result of an algorithm for analysing historical data but rather an organisational process, closely linked to the purchasing practices of the customer. In fact the method relies upon the capabilities of Sales to anticipate future requirements by continuously gathering information from customers and to exchange this subjective information with Manufacturing. The benefits associated with the use of this method can be realised only in an industrial MTO context, when (i) there is a certain amount of information available on customers' anticipated future requests and (ii) the information provided by the customers, during their purchasing process, has some predictive power.