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Click to edit Master title style,Click to edit Master text styles,Second Level,Third Level,Fourth Level,Fifth Level,10-,*, 2007 Pearson Education,Chapter 7Managing Economies of Scale in the Supply Chain: Cycle Inventory,Supply Chain Management,10-,1,Outline,Role of Cycle Inventory in a Supply Chain,Economies of Scale to Exploit Fixed Costs,Economies of Scale to Exploit Quantity Discounts,Short-Term Discounting: Trade Promotions,Estimating Cycle Inventory-Related Costs in Practice,2,第,7,章 获取供应链规模经济的手段：循环库存,一、循环库存在供应链中的作用,二、利用固定成本获取规模经济,三、利用数量折扣获取规模经济,四、短期折扣：商业促销,五、在实践中估测与循环库存相关的费用,3,循环库存产生原因,规模经济,大批量生产与采购,订购与运输,数量折扣与促销,4,Role of Inventory in the Supply Chain,Cost,Availability,Efficiency,Responsiveness,5,Role of Cycle Inventoryin a Supply Chain,Lot, or batch size: quantity that a supply chain stage either produces or orders at a given time,Cycle inventory,: average inventory that builds up in the supply chain because a supply chain stage either produces or purchases in lots that are larger than those demanded by the customer,Q = lot or batch size of an order,D = demand per unit time,Inventory profile: plot of the inventory level over time (Fig. 7.1),Cycle inventory = Q/2 (depends directly on lot size),Average flow time = Avg inventory / Avg flow rate,Average flow time from cycle inventory = Q/(2D),6,Role of Cycle Inventoryin a Supply Chain,Q = 1000 units,D = 100 units/day,Cycle inventory = Q/2 = 1000/2 = 500 = Avg inventory level from cycle inventory,Avg flow time = Q/2D = 1000/(2)(100) = 5 days,Cycle inventory adds 5 days to the time a unit spends in the supply chain,Lower cycle inventory is better because:,Average flow time is lower,Working capital requirements are lower,Lower inventory holding costs,7,Role of Cycle Inventoryin a Supply Chain,Cycle inventory is held primarily to take advantage of economies of scale in the supply chain,Supply chain costs influenced by lot size:,Material cost = C,Fixed ordering cost = S,Holding cost = H = hC (h = cost of holding $1 in inventory for one year),Primary role of cycle inventory,is to allow different stages to purchase product in lot sizes that minimize the sum of material, ordering, and holding costs,Ideally, cycle inventory decisions should consider costs across the entire supply chain, but in practice, each stage generally makes its own supply chain decisions increases total cycle inventory and total costs in the supply chain,8,循环库存在供应链中的作用,循环库存指供应链中建立的平均库存量,Q,：订购批量,R,：单位时间需求量（假设需求量不变）,循环库存批量库存,/2,Q/2,循环库存平均周转时间循环库存,/,需求量,Q/2R,为减少市场波动，公司理想循环库存一般较小,T,Q,9,Economies of Scaleto Exploit Fixed Costs,How do you decide whether to go shopping at a convenience store or at Sams Club?,Lot sizing for a single product (EOQ),10,Economies of Scaleto Exploit Fixed Costs,Annual demand = D,Number of orders per year = D/Q,Annual material cost = CD,Annual order cost = (D/Q)S,Annual holding cost = (Q/2)H = (Q/2)hC,Total annual cost,= TC = CD + (D/Q)S + (Q/2)hC,Figure 7.2 shows variation in different costs for different lot sizes,11,Fixed Costs: Optimal Lot Sizeand Reorder Interval (EOQ),D:Annual demand,S:Setup or Order Cost,C:Cost per unit,h:Holding cost per year as a fraction of product cost,H:Holding cost per unit per year,Q:Lot Size,T:Reorder interval,Material cost is constant and therefore is not considered in this model,12,利用固定成本获取规模经济,单一产品批量规模,Q,（经济订购批量）,R,产品年需求量,S,每次订购固定成本,C,单位产品购买价格成本,H,每年存储成本,年原料价格成本,CR,年订购次数,R/Q,年订购成本（,R/Q,）*,S,年存储成本（,Q/2,）,H=(Q/2)hc,年总成本,TC,CR+,（,R/Q,）*,S+,（,Q/2,）,hc,13,年总成本,TC,CR+,（,R/Q,）*,S+,（,Q/2,）,hc,等式右边对,q,一阶求导，等于,0,时，得最佳订购批量,Q*=,注：,h,和,R,必须要有相同时间单位,n,R/Q*,14,批量规模,成本,总成本,储存成本,订购成本,原材料成本,Q*,15,Example 7.1,Demand, D = 12,000 computers per year,d = 1000 computers/month,Unit cost, C = $500,Holding cost fraction, h = 0.2,Fixed cost, S = $4,000/order,Q* = Sqrt(2)(12000)(4000)/(0.2)(500) = 980 computers,Cycle inventory = Q/2 = 490,Flow time = Q/2d = 980/(2)(1000) = 0.49 month,Reorder interval, T = 0.98 month,16,Example 7.1 (continued),Annual ordering and holding cost =,= (12000/980)(4000) + (980/2)(0.2)(500) = $97,980,Suppose lot size is reduced to Q=200, which would reduce flow time:,Annual ordering and holding cost =,= (12000/200)(4000) + (200/2)(0.2)(500) = $250,000,To make it economically feasible to reduce lot size, the fixed cost associated with each lot would have to be reduced,17,Example 7.2,If desired lot size = Q* = 200 units, what would S haveto be?,D = 12000 units,C = $500,h = 0.2,Use EOQ equation and solve for S:,S = hC(Q*),2,/2D = (0.2)(500)(200),2,/(2)(12000) = $166.67,To reduce optimal lot size by a factor of k, the fixed order cost must be reduced by a factor of k,2,18,例：,best buy,公司采购电脑，月需求,1000,台，固定成本每次,4000,，进价每台,500,，零售商库存成本占,20,，求,Q*,解：年需求量,R=1000*12=12000,每批订购成本,S=4000,单位采购成本,C=500,年存储成本,h,0.2,Q*=,（,2*12000*4000,）,/,（,0.2*500,） ）,1/2,980,循环库存,Q*/2=490,年订购次数,R/Q*=120000/980=12.24,订购和存储成本（,R/Q*,）,S+,（,Q*/2,）,hC=97980,平均周转时间,Q*/2R=490/1200=0.041,年,0.49,月,19,拓展：,A,、如果批量规模,1100,，而不是,980,，则：,订购次数,12000/1100,10.9,总成本,10.9*4000+1100/2*0.2*500,43600+55000,98600,批量规模从,980,到,1100,，增加,10,，总成本从,97980,到,98600,，仅增加,0.6,。,20,B,、假设月需求增加到,4000,每月（增长,4,倍），最佳规模批量和订购次数各自增加,2,倍，平均周转时间减少至,1/2,。,Q*=,年订购次数,R/Q*,平均周转时间,Q*/2R,结论：如果批量规模最佳，需求量增加，循环库存周转时间会减少。,21,C,、如果批量规模为,200,，则：,年库存成本,（,R/Q,）*,S+(Q/2)hC,（,12*1000/200,）,*4000,+,（,200/2,）,0.2*500,=250000 97980,为了减少批量规模，只能减少固定成本。如果期望批量规模为,200,，则,Q*=,S=(hC(Q*,）,2,)/ (2*R),=0.2*500*200*200/(2*12000)=166.7C,1,C,r,The objective for the company (a retailer in our example) is to decide on a lot size that will minimize the sum of material, order, and holding costs,26,All-Unit Quantity Discount Procedure (different from what is in the textbook),Step 1: Calculate the EOQ for the lowest price. If it is feasible (i.e., this order quantity is in the range for that price), then stop. This is the optimal lot size. Calculate TC for this lot size.,Step 2: If the EOQ is not feasible, calculate the TC for this price and the smallest quantity for that price.,Step 3: Calculate the EOQ for the next lowest price. If it is feasible, stop and calculate the TC for that quantity and price.,Step 4: Compare the TC for Steps 2 and 3. Choose the quantity corresponding to the lowest TC.,Step 5: If the EOQ in Step 3 is not feasible, repeat Steps 2, 3, and 4 until a feasible EOQ is found.,27,All-Unit Quantity Discounts: Example,Cost/Unit,$3,$2.96,$2.92,Order Quantity,5,000,10,000,Order Quantity,5,000,10,000,Total Material Cost,28,All-Unit Quantity Discount: Example,Order quantityUnit Price,0-5000$3.00,5001-10000$2.96,Over 10000$2.92,q0 = 0, q1 = 5000, q2 = 10000,C0 = $3.00, C1 = $2.96, C2 = $2.92,D = 120000 units/year, S = $100/lot, h = 0.2,29,All-Unit Quantity Discount: Example,Step 1: Calculate Q2* = Sqrt(2DS)/hC2,= Sqrt(2)(120000)(100)/(0.2)(2.92) = 6410,Not feasible (6410 10001),Calculate TC2 using C2 = $2.92 and q2 = 10001,TC2 = (120000/10001)(100)+(10001/2)(0.2)(2.92)+(120000)(2.92),= $354,520,Step 2: Calculate Q1* = Sqrt(2DS)/hC1,=Sqrt(2)(120000)(100)/(0.2)(2.96) = 6367,Feasible (50006367,10000),Stop,TC1 = (120000/6367)(100)+(6367/2)(0.2)(2.96)+(120000)(2.96),= $358,969,TC2 TC1,The optimal order quantity Q* is q2 = 10001,30,All-Unit Quantity Discounts,Suppose fixed order cost were reduced to $4,Without discount, Q* would be reduced to 1265 units,With discount, optimal lot size would still be 10001 units,What is the effect of such a discount schedule?,Retailers are encouraged to increase the size of their orders,Average inventory (cycle inventory) in the supply chain is increased,Average flow time is increased,Is an all-unit quantity discount an advantage in the supply chain?,31,利用数量折扣获取规模经济,全部单位数量折扣,qiQiqi+1,TCi,（,R/Qi,）,S+(Qi/2)+RCi,32,月需求量,1000,订购成本,100,储存成本,20%,订购数量,单价,0-5000,3,5001-10000,2.96,10000-,2.92,Drug online,33,解：,q0,0,，,q1,5000,，,q2,10000,C0,3,，,C1,2.96,，,C2,2.92,R=120000,S=100,h,0.2,Q0*=(2RS/hC),1/2,(2*120000*100/3*0.2),1/2,6324,q1,5000,时，,TC0=(R/q1)S+(q1/2)hC1+RC1=120000/5000*100+5000/2*0.2*2.96+120000*2.96,359080,Q1*=(2RS/hC),1/2,(2*12000*100/2.96*0.2),1/2,6367,Q1*=6367,时，,TC1=(R/Q1)S+(Q1/2)hC+RC1=,358969,Q2*=(2RS/hC),1/2,(2*12000*100/3*0.2),1/2,6410,q2=10000,时，,TC2=(R/q2)S+(q1/2)hC+RC1=,354520,34,Why Quantity Discounts?,Coordination in the supply chain,Commodity products,Products with demand curve,2-part tariffs,Volume discounts,35,Coordination forCommodity Products,D =,120,000 bottles/year,S,R,= $100,h,R,= 0.2,C,R,= $3,S,S,= $250,h,S,= 0.2,C,S,= $2,Retailers optimal lot size = 6,324 bottles,Retailer cost = $3,795; Supplier cost = $6,009,Supply chain cost = $9,804,36,Coordination forCommodity Products,What can the supplier do to decrease supply chain costs?,Coordinated lot size: 9,165; Retailer cost = $4,059; Supplier cost = $5,106; Supply chain cost = $9,165,Effective pricing schemes,All-unit quantity discount,$3 for lots below 9,165,$2.9978 for lots of 9,165 or more,Pass some fixed cost to retailer (enough that he raises order size from 6,324 to 9,165),37,Quantity Discounts WhenFirm Has Market Power,No inventory related costs,Demand curve,360,000 - 60,000,p,What are the optimal prices and profits in the following situations?,The two stages coordinate the pricing decision,Price = $4, Profit = $240,000, Demand = 120,000,The two stages make the pricing decision independently,Price = $5, Profit = $180,000, Demand = 60,000,38,Two-Part Tariffs andVolume Discounts,Design a two-part tariff that achieves the coordinated solution,Design a volume discount scheme that achieves the coordinated solution,Impact of inventory costs,Pass on some fixed costs with above pricing,39,Lessons from Discounting Schemes,Lot size based discounts increase lot size and cycle inventory in the supply chain,Lot size based discounts are justified to achieve coordination for commodity products,Volume based discounts with some fixed cost passed on to retailer are more effective in general,Volume based discounts are better over rolling horizon,40,为什么采取数量折扣的策略,1,）供应链的协调,如果供应链是纵向一体化，且每一阶段运作均考虑供应链总体利润，则可以实现协调运作，但是，产权的差异，导致各阶段追求各自利益最大化。,41,A,、对最终产品数量折扣,案例,Vitamin co,：,R,10000,，,S,100,，,h,20,，,Cm,3,；,计算出,Q*,6324,，,TC,3795,制造商：,S,250,，,C0,2,，,h,20,。,制造商订购成本,120000/6324*250,4744,制造商年存储成本,6324/2*2*0.2,1265,总成本,4744+1265,6009,供应链总成本,6009+3795,9804,如果,Q*,9165,，则：,供应链总成本,120000/9165*100+9165/2*3,*,0.2+ 120000/9165*250+9165/2*2,*,0.2,4059,+,5106,9165,结论：制造商会通过数量折扣让度部分利益，实现总体利益最大化,42,引论：,以批量折扣为基础的折扣降低了供应链总成本，但增加了零售商采购批量，增加了供应链循环库存。,如果制造商致力于降低其建设成本和订购成本时，规模折扣就会发生改变。但实际情况却是，生产运作部门降低固定成本，营销部门提供数量折扣？！（思考）,43,B,、对公司有市场控制权的产品实行数量折扣,案例：某药品市场需求曲线,q=360000-60000p。,制造商成本,c0=2，,批发价,c1=4。,r,销=（360000-60000,p）p-（360000-60000p）c1,r=360000-120000p+60000c1=0,P=5 q=60000 r,销=60000,r,制=120000,r,供=18000,整合后：,p=4 q=120000 r,供=180000,44,协调方法：,第一种、两部分定价：,制造商先索取全部利润作为前期特许经营费，再将产品以成本出售,第二种、以总量为基础的数量折扣,Q12000,p=3.5,注意：零售商在期末加大采购，即曲棍球现象。,对策：将总量折扣建立在滚动水平基础上（以过去,12,周或者,90,天销售量为基础）,45,2,）利用差别定价使供应链利润最大化,顾客剩余,厂商收益,需求曲线,供给曲线,46,Short-Term Discounting: Trade Promotions,Trade promotions,are price discounts for a limited period of time (also may require specific actions from retailers, such as displays, advertising, etc.),Key goals for promotions from a manufacturers perspective:,Induce retailers to use price discounts, displays, advertising to increase sales,Shift inventory from the manufacturer to the retailer and customer,Defend a brand against competition,Goals are not always achieved by a trade promotion,What is the impact on the behavior of the retailer and on the performance of the supply chain?,Retailer has two primary options in response to a promotion:,Pass through some or all of the promotion to customers to spur sales,Purchase in greater quantity during promotion period to take advantage of temporary price reduction, but pass through very little of savings to customers,47,Short Term Discounting,Q,*,: Normal order quantity,C,: Normal unit cost,d,: Short term discount,D:,Annual demand,h,: Cost of holding $1 per year,Q,d,: Short term order quantity,Forward buy =,Q,d,- Q*,48,Short Term Discounts:Forward Buying,Normal order size,Q,*,= 6,324 bottles,Normal cost,C,= $3 per bottle,Discount per tube,d,= $0.15,Annual demand,D =,120,000,Holding cost,h,= 0.2,Q,d,=,Forward buy =,49,Promotion Pass Throughto Consumers,Demand curve at retailer: 300,000 - 60,000,p,Normal supplier price,C,R,= $3.00,Optimal retail price = $4.00,Customer demand = 60,000,Promotion discount = $0.15,Optimal retail price = $3.925,Customer demand = 64,500,Retailer only passes through half the promotion discount and demand increases by only 7.5%,50,Trade Promotions,When a manufacturer offers a promotion, the goal for the manufacturer is to take actions (countermeasures) to discourage forward buying in the supply chain,Counter measures,EDLP,Scan based promotions,Customer coupons,51,短期折扣：商业促销,制造商目的：引导零售商通过价格折扣、展示或者广告宣传刺激销售；制造商库存转移；品牌竞争,经销商选择：,将一部分或者全部促销优惠让度给消费者，刺激销售；只是让度一小部分，大批购进，缓慢销售。,52,折扣价格下的最优订购数量：,假设：折扣仅提供一次；,Qd,是,Q*,的倍数；零售商不将优惠让度给顾客。,Qd,dR/,（,C-d,）,h+CQ*/(C-d),超前采购量,Qd- Q*,如果零售商知道下一个促销时间，设为,Q1,，则会选择,Q1,和,Qd,的最小值。,53,案例：,DO,公司,R=120000,CM=3,h,0.2,，,Q*=6324,d,0.15,，求零售商订购数量？,Qd,dR/,（,C-d,）,h+CQ*/(C-d),0.15*120000/,（,3-0.15,）,0.2+3*6324/,（,3-0.15,）,38236,循环库存,19118,平均周转时间,38236/2*120000,0.16,年,1.9118,月,超前采购量,38236-6324,31912,DO,公司在今后,3,个月将不采购！导致零售商库存大增。只有当制造商无意建立了大量剩余库存，或者想使低谷期需求量增加，才会支持超前采购。实际上，制造商经常根据预测的计划促销活动建立库存。,54,总结：,1,、商业促销通常会增加循环库存，损害供应链利益，许多公司，如,walm,，,P&G,采用,low price every day,，而不提供短期折扣。,2,、商业促销作为,竞争性反应,是有用的，如,peps,，,& cocal,3,、管理者应当精心设计促销，限制超前采购，并刺激更多的向顾客价值让度,4,、充分运用现代信息技术，以零售扫描数据为基础实施折扣；或者按以往销售业绩，分配折扣商品数量。,55,Estimating Cycle Inventory-Related Costs in Practice,Inventory holding cost,Cost of capital,Obsolescence cost,Handling cost,Occupancy cost,Miscellaneous costs,Order cost,Buyer time,Transportation costs,Receiving costs,Other costs,56,Levers to Reduce Lot Sizes Without Hurting Costs,Cycle Inventory Reduction,Reduce transfer and production lot sizes,Aggregate fixed costs across multiple products, supply points, or delivery points,Are quantity discounts consistent with manufacturing and logistics operations?,Volume discounts on rolling horizon,Two-part tariff,Are trade promotions essential?,EDLP,Based on sell-thru rather than sell-in,57,在实践中估测与循环库存相关的费用,1,、库存存储成本,资本成本：股本成本、债务成本和税收抵免,报废成本：质量退化和过时,管理成本：接收和储存管理成本（阶梯性）,空间占用成本（阶梯性）,2,、订购成本,采购员时间,运输费用,接收成本,其他成本,58,Summary of Learning Objectives,How are the appropriate costs balanced to choose the optimal amount of cycle inventory in the supply chain?,What are the effects of quantity discounts on lot size and cycle inventory?,What are appropriate discounting schemes for the supply chain, taking into account cycle inventory?,What are the effects of trade promotions on lot size and cycle inventory?,What are managerial levers that can reduce lot size and cycle inventory without increasing costs?,59,
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