《供应链管理教学》第4章信息的价值_供应链管理

1、2牛鞭效应牛鞭效应有效预测有效预测协调系统的信息协调系统的信息找出所需产品找出所需产品缩短提前期缩短提前期信息和供应链的权衡信息和供应链的权衡3我们生活在信息的时代中“In modern supply chains, information replaces inventory”（信息取代了库存）Why is this true?Why is this false?Information is always better than no information信息如何影响供应链的设计与运作通过有效地利用可取得的信息，我们可以比以前更有效益及更有效率地设计与运作供应链4丰富的信息将Helps r

2、educe variability（协助减少供应链的变动性）Helps improve forecasts （协助供货商作出更好的预测）Enables coordination of systems and strategies （使制造和分销系统与策略能够协调）Improves customer service （通过提供定位所需商品的工具，使零售商为顾客提供更好的服务）Facilitates lead time reductions （能减少提前期）Enables firms to react more quickly to changing market conditions （使零售商

3、能更快地反应并适应供应方面的问题）5在供应链中愈往上游走，订单数量变动性愈增大的现象就是牛鞭效应Order variability is amplified up the supply chain; upstream echelons face higher variabilityWhat you see is not what they face6一个简单的四级供应链一个零售商一个批发商一个分销商一个工厂7零售商所下的订单的变动会比顾客需求高，批发商被迫持有较零售商多的安全库存，或必须要能较零售商保持更高的能力以维持同样的服务水平8需求预测（Demand Forecasting）Order-

4、up-to points are modified as forecasts change orders increase more than forecasts提前期（Lead Time）Long lead times magnify this effect批量订购（Batching）Volume and transportation discounts价格波动（Price Fluctuation）被夸大的订单（Inflated Orders）IBM Aptiva orders increased by 2-3 times when retailers thought that IBM wo

5、uld be out of stock over ChristmasMotorola cell phones9Exists, in part, due to the retailers need to estimate the mean and variance of demandThe increase in variability is an increasing function of the lead timeThe more complicated the demand models and the forecasting techniques, the greater the in

6、creaseCentralized demand information can significantly reduce the bullwhip effect, but will not eliminate itQuantifying the BullwhipConsider a two-stage supply chain:Retailer who observes customer demandRetailer places an order to a manufacturer. Retailer faces a fixed lead timeorder placed at the e

7、nd of period t Order received at the start of period t+L. Retailer follows a simple periodic review policy retailer reviews inventory every periodplaces an order to bring its inventory level up to a target level. the review period is one10Quantifying the BullwhipBase-Stock Level = L x AVG + z x STD

8、x LOrder up-to point =If the retailer uses a moving average technique, with p observations to forecast demand ttLSzL tpDtptii11)(122pDStptitit11Quantifying the Increase in VariabilityVar(D), variance of the customer demand seen by the retailer Var(Q), variance of the orders placed by that retailer t

9、o the manufacturerWhen p is large and L is small, the bullwhip effect is negligible.Effect is magnified as we increase the lead time and decrease p.22221)()(pLpLDVarQVar12Lower Bound on the Increase in Variability Given as a Function of pFIGURE 5-7: A lower bound on the increase in variability given

10、 as a function of p13Impact of Variability ExampleAssume p = 5, L=1Assume p = 10, L=1Increasing p the number of observations used in the moving average forecast reduces the variability of the retailer order to the manufacturer4.1)()(DVarQVar2.1)()(DVarQVar1415最常被提出降低牛鞭效应的建议就是在供应链中集中需求的信息根据实际的顾客需求，在供

11、应链每一个级提供完整的信息若需求信息是集中化的，那么在供应链中的每一个级都可使用正确的顾客需求数据，并以此产生正确的预测，而不是依赖前几个级传来的订单，而其可能会比真实的顾客需求变动的更多16为了决定牛鞭效应里集中化需求信息的影响，我们将区分两种不同型态的供应链：集中式的需求信息分布式的需求信息17在集中式供应链中，供应链中的每一个级收到零售商所预测的平均需求，并根据这个平均需求确定库存上限水平的库存政策在此情形下，将需求的信息、预测的技术及库存政策集中化处理供应链中某一级所下订单的方差是该级与零售商之间全部提前期的递增函数Variability with Centralized Inform

12、ationVar(D), variance of the customer demand seen by the retailer Var(Qk), variance of the orders placed by the kth stage to itsLi, lead time between stage i and stage i + 1Variance of the orders placed by a given stage of a supply chain is an increasing function of the total lead time between that

13、stage and the retailer 2211)( 221)()(pLpLDVarQVarkiikiik1819分布式供应链中，零售商不提供他所预测的平均需求给供应链中的其它主体批发商必须要根据从零售商那里收到的订单，计算平均需求在分布式供应链中，只有零售商知道顾客的需求，所以会比集中式供应链具更多的变动而在集中式供应链中，供应链中的任何级都可得到顾客需求信息因此，可以推断集中式的需求信息可以降低牛鞭效应供应链中某一级所下订单的方差是以乘积的方式在增加Variability with Decentralized InformationRetailer does not make its

14、 forecast information available to the remainder of the supply chainOther stages have to use the order informationVariance of the orders: becomes larger up the supply chain increases multiplicatively at each stage of the supply chain. )221 ()()(221pLpLDVarQVarikiik20Managerial InsightsVariance incre

15、ases up the supply chain in both centralized and decentralized casesVariance increases:Additively with centralized caseMultiplicatively with decentralized caseCentralizing demand information can significantly reduce the bullwhip effect Although not eliminate it completely!21Increase in Variability f

16、or Centralized and Decentralized Systems FIGURE 5-8: Increase in variability for centralized and decentralized systems2223降低不确定性（Reduce uncertainty）POSSharing informationSharing forecasts and policies降低变动性（Reduce variability）Eliminate promotionsEvery-day low pricing (EDLP)减少提前期（Reduce lead times）EDI

17、Cross docking战略伙伴关系（Strategic partnerships）Vendor managed inventory (VMI)Data sharing24Benetton, the Italian sportswear manufacturer, was founded in 1964. In 1975 Benetton had 200 stores across Italy.Ten years later, the company expanded to the US, Japan and Eastern Europe. Sales in 1991 reached 2 t

18、rillion.Many attribute Benettons success to successful use of communication and information technologies.25Benetton uses an effective strategy, referred to as Quick Response, in which manufacturing, warehousing, sales and retailers are linked together.In this strategy a Benetton retailer reorders a

19、product through a direct link with Benettons mainframe computer in Italy.Using this strategy, Benetton is capable of shipping a new order in only four weeks, several week earlier than most of its competitors.26Integrated Information SystemsGlobal EDI network that links agents with production and inv

20、entory informationEDI order transmission to headquartersEDI linkage with air carriersData linked to manufacturingCoordinated PlanningFrequent review allows fast reactionIntegrated distribution strategyInformation Sharing And Incentives Centralizing information will reduce variabilityUpstream stages

21、would benefit moreUnfortunately, information sharing is a problem in many industriesInflated forecasts are a realityForecast information is inaccurate and distortedForecasts inflated such that suppliers build capacitySuppliers may ignore the forecasts totally27Contractual Incentives to Get True Fore

22、casts from BuyersCapacity Reservation ContractBuyer pays to reserve a certain level of capacity at the supplierA menu of prices for different capacity reservations provided by supplierBuyer signals true forecast by reserving a specific capacity levelAdvance Purchase ContractSupplier charges special

23、price before building capacityWhen demand is realized, price charged is differentBuyers commitment to paying the special price reveals the buyers true forecast2829信息导致更有效的预测愈多未来需求的因素能够被加以考虑，预测的正确性就越高Pricing, Promotion, New ProductsDifferent parties have this informationRetailers may set pricing or p

24、romotion without telling distributorDistributor/Manufacturer might have new product or availability information30许多供应链正向联合预测系统（Collaborative Forecasting Systems）迈进在这些系统中，复杂的信息系统提供了一个反复的预测程序，使供应链中的参与者透过合作能够达到对预测有一致的共识这暗示了供应链所有的参与者分享并使用相同的预测工具，从而导致牛鞭效应的降低31在任何的供应链当中有许多系统，包含了不同的制造、仓储、运输以及零售系统所有这些系统是连结在

25、一起的。进一步来看，这些来自供应链当中一个系统的产出是下一个系统的投入因此，试着为任何一个阶段找寻最佳效益背反的答案是不够的。我们需要考虑整个系统并协调相关决策32Information is required to move from local to global optimisation当系统不协调时也就是每一个供应链当中的成员追求自己最大的利益其结果是局部最佳化供应链的每一个成员只寻求自己运作的最佳化，而不去注意本身的政策对供应链其它成员的影响相对于上述方式的是全局最优化全局最优化意味去确认什么才是对整个系统最好的做法33有两个议题需要被注意：Who will optimise：谁来做

26、最佳化？How will savings be split：如何使透过协调的策略而节省下的成本能在不同供应链的成员之间彼此分享？Information is needed :Production status and costsTransportation availability and costsInventory informationCapacity informationDemand information34How can demand be met if products are not in inventory?Locating products at other stores

27、What about at other dealers?有很多种方式可以满足顾客的需求。 对一个库存式生产系统（Made to Stock）而言，我们希望从零售的库存来满足顾客需求但能够找出且配送产品，有时与拥有库存一样有效但如果商品是在零售商的竞争者手中，这些竞争者是否愿意为零售商调拨商品则不是很明朗35缩短提前期的重要性是不能被忽视的。它通常会导致：Customer orders are filled quickly：快速满足无法以库存来满足顾客订单的能力Bullwhip effect is reduced：减少牛鞭效应Forecasts are more accurate：因为预测期的缩

28、减，带来更正确的预测结果Inventory levels are reduced：减少产成品的库存水平36为了这些理由，许多厂商正积极地寻求具备更短提前期的供货商，而且许多潜在的顾客认为提前期对于供货商的选择是一个非常重要的标准二十世纪晚期许多制造革命导致提前期的减少，这些设计能够存在是因为整个供应链的状态信息可被获取例如EDI系统藉由减少提前期的成份如订单流程、纸质作业、库存分拣等来缩短提前期用POS系统自零售商传送数据到供货商能够协助减少提前期，是因为供货商能够透过POS系统的数据来预测将要到来的订单37供应链不同级经理人间均有冲突的目标，而对供应链中不同级的整合或协作也造成了冲突甚至在一

29、个级中，降低库存水平或运输成本的效益背反，或是增加产品多样性的效益背反也常常出现通过仔细利用可获得的信息，供应链可以更趋近于全局最优化，并依据不同冲突目标和不同效益背反，降低整个系统的成本38原料供货商制造管理物料、仓库、外向物流管理零售商顾客稳定的需求、所需物料组合几乎不变、可灵活变动的交货期、大量的需求高生产率、低生产成本、需求模式提前已知且没有什么变动利用数量折扣最小化运输成本、最小化库存和快速补充库存商品有存货、种类多、价格低短的订货提前期、有效率的正确交货39在过去，为了达成某些目标，另外一些目标必须要被牺牲。供应链被视为是一连串要决定的效益背反现在可获得大量的信息来设计供应链，使其

30、能接近达到这些表面上看来是冲突的目标一些在几年前被认为是在供应链中存在的效益背反，现在已不再互相抵触40这些效益背反，及这些效益背反如何通过先进技术及创新的网络设计，使得他们在现代供应链中不会再有效益背反或至少被降低批量大小 库存的效益背反（Lot Size Inventory）Advanced manufacturing systemsPOS data for advance warnings库存 运输成本效益背反（Inventory Transportation）Lead time reduction for batchingInformation systems for combining shipmentsCross dockingAdvanced DSS41提前期 运输成本（Lead Time Transportation）Lower transportation costsImproved forecastingLower order lea