供应链管理Chapter4

1、Chapter 4 The Value of Information 4.1 Introduction 1. “In modern supply chains, information replaces inventory”Why is this true?Why is this false? 2. Information is always better than no information. Why? InformationHelps reduce variabilityHelps improve forecastsEnables coordination of systems and

2、strategiesImproves customer serviceFacilitates lead time reductionsEnables firms to react more quickly to changing market conditions.4.2 The Bullwhip Effect and its Impact on the Supply Chain External Demand Order lead time Delivery lead time Order lead time Delivery lead time Order lead time Delive

3、ry lead time Production lead time Retailer Wholesaler Distributor Factory Increasing Variability of Orders Up the Supply ChainLee, H, P. Padmanabhan and S. Wang (1997), Sloan Management Review4.2.1 The Bullwhip Effect Order variability is amplified up the supply chain; upstream echelons face higher

4、variability. 随着往供应链上游前进需求变动程序增大随着往供应链上游前进需求变动程序增大的现象即著名的的现象即著名的 “牛鞭效应牛鞭效应”.Consequences. Increased safety stock Reduced service level Inefficient allocation of resources Increased transportation costsExample: a simple supply chain Single retailer, single manufacturer Average annual demand is 5,200 u

5、nits, and shipments are made to the store each week. If the variability in orders placed is low, so that the shipment every week is capacity need by only about 100 units. If weekly variability is very high, so that during certain weeks makers must make and ship 400 units and weeks no units at all, i

6、t is easy to see that production and shipping capacity must be much higher and that some weeks is capacity will be idle. What are the Causes. Promotional sales Forward buying Volume and transportation discounts Batching Inflated orders IBM Aptiva orders increased by 2-3 times when retailers thought

7、that IBM would be out of stock over ChristmasWhat are the Causes. Demand forecasting Order-up-to points are modified as forecasts change orders increase more than forecasts Long cycle times Long lead times magnify this effect4.2.2 牛鞭效应的理论基础牛鞭效应的理论基础沿着供应链上游移动，需求变动程度不断增大的现象沿着供应链上游移动，需求变动程度不断增大的现象 VAR(

8、D) VAR(Q1) VAR(Q2) 1, VAR(Q2)/VAR(Q1)1, VAR(Q3)/VAR(Q2)1 the variance of the customer demand seen by the retailer is VAR(D)制制造造者者批批发发商商销销售售商商零零售售商商订货订货订货订货订货订货商品商品商品商品商品商品Q1Q2Q3D 假设零售商用（假设零售商用（s，S）订货策略）订货策略 供应商用最近的供应商用最近的p个零售商的定单数据来估计零售商个零售商的定单数据来估计零售商的需求的需求 需求需求D的方差与定货量的方差与定货量Q的方差之比反应了牛鞭效应的方差之比反应了牛

9、鞭效应的大小的大小VAR（Q）VAR（D）1 + +2Lp2Lp22-提前期提前期 L=0, 牛鞭效应为零牛鞭效应为零-提前期提前期 L 越大，越大，VAR(Q) 越大于越大于VAR(D)，牛鞭效应，牛鞭效应越大越大-抽样数据量抽样数据量 p 越小，牛鞭效应越大越小，牛鞭效应越大牛鞭效应：牛鞭效应：1.多级信息分散的供应链的牛鞭效应多级信息分散的供应链的牛鞭效应 每级用前级的定单的方差来确定定单量每级用前级的定单的方差来确定定单量 牛鞭效应为方差比牛鞭效应为方差比 分散多级供应链的牛鞭效应与级数成指数关系分散多级供应链的牛鞭效应与级数成指数关系 级数越大，牛鞭效应也越大级数越大，牛鞭效应也越大

10、级级k级级k-1级级3级级2级级1DQQQQQ123k-2k-1LLLLLk-1k-2321VAR(Q ) VAR(Q ) VAR(D )VAR(Q )VAR(D)k-1 =VAR(Q ) VAR(Q ) VAR(Q )k-1k-2321= ( 1 + + )i=1k-12L2Lii2pp2k-1VAR(Q )/VAR(D)2.集中需求信息对牛鞭效应的影响集中需求信息对牛鞭效应的影响 集中信息的集中信息的K级供应链级供应链 每一级向上一级提供定单与零售商的需求预测信息每一级向上一级提供定单与零售商的需求预测信息D 每一级用零售商的预测每一级用零售商的预测D与累积的提前期来确定订货量与累积的提前

11、期来确定订货量 牛鞭效应为牛鞭效应为 集中信息的供应链的牛鞭效应与总提前期成比例集中信息的供应链的牛鞭效应与总提前期成比例VAR(D)k-1VAR(Q )k-11 + + 2( L )i=12 Li=1k-1ii2pp2D级级k级级k-1级级3级级2级级1DQQQQQ123k-2k-1LLLLLk-1k-2321DDDD3. 需求信息对多级供应链的牛鞭效应的影响需求信息对多级供应链的牛鞭效应的影响 分散信息的供应链分散信息的供应链 牛鞭效应与级数成指数关系牛鞭效应与级数成指数关系 集中信息的供应链集中信息的供应链 牛鞭效应与级数无关，只与总提前期成比例牛鞭效应与级数无关，只与总提前期成比例 结

12、论结论 集中信息能显著减少牛鞭效应集中信息能显著减少牛鞭效应 集中信息的供应链的牛鞭小于分散信息的供集中信息的供应链的牛鞭小于分散信息的供应链的牛鞭应链的牛鞭 集中信息并不能消除牛鞭效应集中信息并不能消除牛鞭效应4.2.3 Coping with the Bullwhip Effect in Leading Companies 1. Reduce uncertainty POS Sharing information Sharing forecasts and policies 2. Reduce variability Eliminate promotions Year-round low

13、pricing 3. Reduce lead times EDI Cross docking 4.Strategic partnerships Vendor managed inventory (VMI) Data sharingExample: Quick Response at Benetton Benetton, the Italian sportswear manufacturer, was founded in 1964. In 1975 Benetton had 200 stores across Italy. Ten years later, the company expand

14、ed to the U.S., Japan and Eastern Europe. Sales in 1991 reached 2 trillion. Many attribute Benettons success to successful use of communication and information technologies.Example:Quick Response at Benetton Benetton uses an effective strategy, referred to as Quick Response, in which manufacturing,

15、warehousing, sales and retailers are linked together. In this strategy a Benetton retailer reorders a product through a direct link with Benettons mainframe computer in Italy. Using this strategy, Benetton is capable of shipping a new order in only 4 weeks, several week earlier than most of its comp

16、etitors.How Does BenettonCope with the Bullwhip Effect?1. Integrated Information Systems Global EDI network that links agents with production and inventory information EDI order transmission to HQ EDI linkage with air carriers Data linked to manufacturing2. Coordinated Planning Frequent review allow

17、s fast reaction Integrated distribution strategy4.3 Information for Effective Forecasts Pricing, promotion, new products Different parties have this information Retailers may set pricing or promotion without telling distributor Distributor/Manufacturer might have new product or availability informat

18、ion Collaborative Forecasting（合作预测）（合作预测） addresses these issues.4.4 Information for Coordination of Systems Information is required to move from local to global optimization Questions: Who will optimize? How will savings be split? Information is needed : Production status and costs Transportation a

19、vailability and costs Inventory information Capacity information Demand information4.5 Locating Desired Products How can demand be met if products are not in inventory? Locating products at other stores What about at other dealers? What level of customer service will be perceived?4.6 Lead-Time Reduction Why? Customer orders are filled quickly Bullwhip effect is reduced Forecasts are more accurate Inventory levels are reduced How? EDI POS data leading to anticipating