Porter's Value Chain模型相比PEST更加具有灵活性.

　　这个战略模型能帮助我们有效地分解商业周期到可以对于企业商品或服务增值的战略活动中。通过一系列分析，公司可以定义哪儿的成本太高、哪儿更有效同时从竞争者中了解到我方的差异。在商业信息的管理下，公司也能根据信息系统的反馈做出具有竞争优势的决策。

　　以下我们通过一个例子来学习：

　　Example - Handling physical goods

　　Inbound logistics may be met by automated warehouse procedures for manufacturing, or by a dedicated transport fleet for shipping stock into branch stores.

　　Operations would be controlled by a manufacturing system, such as a production scheduling system, or by a stacking and selling process in a retail business

　　Outward logistics could be handled by a delivery fleet, a transport scheduling system or a collection point.

　　Although Porter defined the Value Chain as pertaining to both products and services, most textbooks simply describe the physical aspects, as reflected in the descriptions above. The terms 'Inbound logistics' and 'Outbound logistics' give emphasis to the idea of physical movement. Services, however, are less tangible, so we need to examine whether the Value Chain model can still be applied. Service sectors include financial services, travel and tourism, marketing, and advertising.

　　Any service must have identifiable inputs and outputs. Inbound and outbound logistics refer to the input and output to and from the process part of the system. Our other primary activities of marketing, sales and service also feed into the process, but not in the same manner, hence their separate boxes on the process model.

　　Considered in this way, we can reconsider our view of the Value Chain as only appraising the cost of handling physical goods. So what can we see from this view? Here's an example of a training company that specialises in providing online learning rather than traditional classroom instruction. The source for this is a study undertaken by Woudstra and Powell in 1989.

　　Rather than talk in terms of logistics, we need to consider what represents the inputs to, and outputs from, the process. One way to approach this is to list some of what we (ie the business) consider to be the core activities, and see how they map onto the process model.

　　Once the activities have been identified and the model populated, the business can analyse the costs of each element, as in the traditional model.

　　This example shows how a company selling a largely intangible service still has to control its value chain in order to manipulate its costs to maximum effect. In the current economy, where service industries generate as much money as manufacturing, it is important to be able to recognise the primary activities in these sectors, and how they can be appraised.

　　By Malcolm Eva