Ch07_Pindyck生产成本

1、Chapter 7成本2005 Pearson Education, Inc.Topics to be Discussedl衡量成本?l短期成本l长期成本l长期和短期成本曲线22005 Pearson Education, Inc.Topics to be DiscussedlProduction with Two Outputs: Economies of Scope规模经济lDynamic Changes in Costs: The Learning Curve长期成本曲线32005 Pearson Education, Inc.5.1衡量成本衡量成本lFor a firm to mini

2、mize costs, we must clarify what is meant by costs and how to measure themmIt is clear that if a firm has to rent equipment or buildings, the rent they pay is a costmWhat if a firm owns its own equipment or building?lHow are costs calculated here?42005 Pearson Education, Inc.Measuring Cost:Which Cos

3、ts Matter?lAccounting Cost会计成本会计成本m实际发生的费用和固定资产的折旧实际发生的费用和固定资产的折旧lEconomic Cost经济成本经济成本m企业在生产中所使用的资源的成本企业在生产中所使用的资源的成本52005 Pearson Education, Inc.Measuring Cost:Which Costs Matter?lOpportunity cost机会成本机会成本m企业未将资源用于其他可供选择的最佳用途而放弃的机会相联系的成本62005 Pearson Education, Inc.Measuring Cost:Which Costs Matter

4、?l Although opportunity costs are hidden and should be taken into account, sunk costs should notl Sunk Cost沉没成本沉没成本m已经发生但无法收回的支出已经发生但无法收回的支出m在制定未来经济决策时应当忽略它在制定未来经济决策时应当忽略它。72005 Pearson Education, Inc.Sunk CostlFirm buys a piece of equipment that cannot be converted to another use专用设备lExpenditure on

5、 the equipment is a sunk costmHas no alternative use so cost cannot be recovered opportunity cost is zeromDecision to buy the equipment might have been good or bad, but now does not matter82005 Pearson Education, Inc.Prospective Sunk CostlAn ExamplemFirm is considering moving its headquartersmA firm

6、 paid $500,000 for an option to buy a buildingmThe cost of the building is $5 million for a total of $5.5 millionmThe firm finds another building for $5.25 millionmWhich building should the firm buy?92005 Pearson Education, Inc.Prospective Sunk CostlExample (cont.)lThe first building should be purch

7、asedlThe $500,000 is a sunk cost and should not be considered in the decision to buylWhat should be considered ismSpending an additional $5,250,000 ormSpending an additional $5,000,000102005 Pearson Education, Inc.Measuring Cost:Which Costs Matter?l总成本包括总成本包括:1. Fixed Cost固定成本固定成本mDoes not vary with

8、 the level of output2. Variable Cost 可变成本可变成本mCost that varies as output varies VC FC TC112005 Pearson Education, Inc.Fixed and Variable Costsl什么成本是固定的，什么是可变的，和时什么成本是固定的，什么是可变的，和时间长短有关间长短有关l在短期内大多数成本固定在短期内大多数成本固定l长期内大多数成本可变长期内大多数成本可变122005 Pearson Education, Inc.固定成本与沉没成本固定成本与沉没成本l 他们经常被混淆他们经常被混淆l F

9、ixed Costm在企业经营中必须支付的成本，与产出在企业经营中必须支付的成本，与产出水平无关水平无关m影响企业决策影响企业决策l Sunk Cost m已经发生无法收回的成本。不影响决策已经发生无法收回的成本。不影响决策m将沉淀成本按摊销方式处理。不区分沉将沉淀成本按摊销方式处理。不区分沉淀成本和固定成本淀成本和固定成本132005 Pearson Education, Inc.边际成本边际成本lMarginal Cost (MC):mThe cost of expanding output by one unitmFixed costs have no impact on margina

10、l cost, so it can be written as:qTCqVC MC 142005 Pearson Education, Inc.平均成本平均成本lAverage Total Cost (ATC)mCost per unit of outputmAlso equals average fixed cost (AFC) plus average variable cost (AVC)qTVCqTFCqTC ATC AVCAFC qTC ATC 152005 Pearson Education, Inc.7.2短期成本短期成本162005 Pearson Education, Inc

11、.短期成本的决定因素短期成本的决定因素 An xamplel考察生产与成本的关系l假设工资固定lVC= wLqLwqVC MC172005 Pearson Education, Inc.Determinants of Short Run Costs An Examplel因为LMP LQLL1L for a 1 unit Q QMPl获得额外一单位产出所需要的额外的劳动数量为182005 Pearson Education, Inc.Determinants of Short Run Costs An Examplel所以所以LMP MCwl较低的劳动边际产量较低的劳动边际产量(MPL)味着较

12、高味着较高的边际成本的边际成本 (MC)。每当劳动的边际产。每当劳动的边际产量降低时，边际成本上升量降低时，边际成本上升短期内，边际成本等于变化的投短期内，边际成本等于变化的投入要素的价格除以其边际产量入要素的价格除以其边际产量192005 Pearson Education, Inc.边际报酬递减和边际成本边际报酬递减和边际成本l边际报酬递减边际产量下降边际成本上升202005 Pearson Education, Inc.成本曲线成本曲线OutputCost($ peryear)100200300400012345678910111213VCVariable costincreases w

13、ith production andthe rate varies withincreasing anddecreasing returns.TCTotal costis the verticalsum of FC and VC.FC50Fixed cost does notvary with output212005 Pearson Education, Inc.Cost Curves020406080100120024681012Output (units/yr)Cost ($/unit)MCATCAVCAFC222005 Pearson Education, Inc.Cost Curve

14、slWhen MC is below AVC, AVC is fallinglWhen MC is above AVC, AVC is risinglWhen MC is below ATC, ATC is fallinglWhen MC is above ATC, ATC is risinglTherefore, MC crosses AVC and ATC at the minimumsmThe Average Marginal relationship232005 Pearson Education, Inc.Cost Curves for a Firml The line drawn

15、from the origin to the variable cost curve:mIts slope equals AVCmThe slope of a point on VC or TC equals MCmTherefore, MC = AVC at 7 units of output (point A)12345678910111213OutputP100200300400FCVCTCA242005 Pearson Education, Inc.7.3长期成本长期成本l长期内厂商能改变所有投入要素，因长期内厂商能改变所有投入要素，因而改变规模而改变规模l为了实现成本最小化，厂商需要

16、选择为了实现成本最小化，厂商需要选择合适的投入要素组合合适的投入要素组合252005 Pearson Education, Inc.Cost in the Long Runl租入资本=自有资本lAssume Delta is considering purchasing an airplane for $150 millionmPlane lasts for 30 yearsm$5 million per year economic depreciation for the plane262005 Pearson Education, Inc.Cost in the Long Runl如果场上

17、没有购买飞机则可以将资本如果场上没有购买飞机则可以将资本存银行获得利息收入存银行获得利息收入 $150 millionl这是机会成本这是机会成本l使用者成本使用者成本=机会成本机会成本+经济折旧经济折旧=利率利率*资产价值资产价值+经济折旧经济折旧272005 Pearson Education, Inc.Cost in the Long RunlUser Cost of Capital = Economic Depreciation + (Interest Rate)*(Value of Capital)l= $5 mil + (.10)($150 mil depreciation)mYea

18、r 1 = $5 million + (.10)($150 million) = $20 millionmYear 10 = $5 million +(.10)($100 million) = $15 million282005 Pearson Education, Inc.Cost in the Long Runl每单位资本的使用者成本：每单位资本的使用者成本：lr=折旧率折旧率+利率利率lIn our example, depreciation rate was 3.33% and interest was 10%, so mr = 3.33% + 10% = 13.33%292005 P

19、earson Education, Inc.成本最小化的投入选择成本最小化的投入选择l 假设：两个可变投入假设：两个可变投入: Labor (L) and capital (K)m劳动的价格：工资劳动的价格：工资 (w)m资本的价格：资本的价格：r = 折旧率折旧率 +利率（使利率（使用者成本）用者成本）lOr 资本价格：资本价格：=租金率租金率r302005 Pearson Education, Inc.Cost in the Long Runl等成本线等成本线C = wL + rK312005 Pearson Education, Inc.Cost in the Long RunlRewr

20、iting C as an equation for a straight line:mK = C/r - (w/r)Lm等成本线的斜率等成本线的斜率=-(w/r)rwLK322005 Pearson Education, Inc.给定产量的成本最小化给定产量的成本最小化Labor per yearCapitalperyearIsocost C2 shows quantity Q1 can be produced withcombination K2,L2 or K3,L3.However, both of theseare higher cost combinationsthan K1,L1

21、.Q1Q1 is an isoquant for output Q1.There are three isocost lines, of which 2 are possible choices in which to produce Q1.C0C1C2AK1L1K3L3K2L2332005 Pearson Education, Inc.Input Substitution When an Input Price Change：劳动价格上：劳动价格上升升C2The new combination of K and L is used to produce Q1.Combination B is

22、 used in place of combination A.K2L2BC1K1L1AQ1If the price of laborrises, the isocost curvebecomes steeper due to the change in the slope -(w/L).Labor per yearCapitalperyear342005 Pearson Education, Inc.Cost in the Long Runl成本最小化的条件成本最小化的条件KLMPMP- MRTSLKrwLK lineisocost of Slopecostminimizesfirmwhen

23、rwMPMPKL352005 Pearson Education, Inc.Cost in the Long RunlThe minimum cost combination can then be written as:rwKLMPMP362005 Pearson Education, Inc.扩张路径扩张路径Expansion PathThe expansion path illustratesthe least-cost combinations oflabor and capital that can be used to produce each level ofoutput in

24、the long-run.Capitalperyear25507510015050Labor per year100150300200A$2000200 UnitsB$3000300 UnitsC372005 Pearson Education, Inc.Expansion Path and Long Run Costsl扩张路径描述了长期生产中每一给定产量是能够使得成本最低的劳动和资本组合。从中可以得到长期总成本曲线。382005 Pearson Education, Inc.A Firms Long Run Total Cost CurveLong Run Total CostOutput

25、, Units/yr100300200Cost/ Year100020003000DEF392005 Pearson Education, Inc.7.4长期和短期成本曲线长期和短期成本曲线l在短期内，有部分固定投入在短期内，有部分固定投入l厂商在长期内所有投入要素可变厂商在长期内所有投入要素可变m在长期内，企业能够以比短期生产在长期内，企业能够以比短期生产更低的平均成本进行生产更低的平均成本进行生产402005 Pearson Education, Inc.Capital is fixed at K1.To produce q1, min cost at K1,L1.If increase

26、output to Q2, min costis K1 and L3 in short run.The Inflexibility of Short Run ProductionLong-RunExpansion PathLabor per yearCapitalperyearL2Q2K2DCFEQ1ABL1K1L3PShort-RunExpansion PathIn LR, can change capital and min costs falls to K2 and L2.412005 Pearson Education, Inc.Long Run VersusShort Run Cos

27、t Curvesl LACm决定长期平均成本决定长期平均成本 L AC和边和边际成本际成本 MC 形状的因素是规模形状的因素是规模报酬递减规律。报酬递减规律。1. 规模报酬不变规模报酬不变长期平均成本曲长期平均成本曲线和边际成本曲线水平，是常数。线和边际成本曲线水平，是常数。422005 Pearson Education, Inc.Long Run Versus Short Run Cost Curves2. 规模报酬递增规模报酬递增长期平均和边长期平均和边际成本曲线下右下方倾斜际成本曲线下右下方倾斜3. 规模报酬递减规模报酬递减长期成曲线向长期成曲线向右上倾斜、右上倾斜、4. 长期成本曲线

28、也是长期成本曲线也是U型的。型的。432005 Pearson Education, Inc.Long Run Versus Short Run Cost Curvesl长期边际成本石油长期平均成本决定的:mIf LMC LAC, LAC will risemTherefore, LMC = LAC at the minimum of LACl当 LAC不变时， LAC and LMC 相等442005 Pearson Education, Inc.Long Run Average and Marginal CostOutputCost($ per unitof outputLACLMCA45

29、2005 Pearson Education, Inc.规模经济和规模不经济规模经济和规模不经济l规模经济mIncrease in output is greater than the increase in inputsl规模不经济mIncrease in output is less than the increase in inputslU-shaped LAC shows economies of scale for relatively low output levels and diseconomies of scale for higher levels462005 Pearso

30、n Education, Inc.Long Run Costsl规模经济以成本-产出弹性衡量 ECACMCQQCCECEC1，规模不经济，规模不经济472005 Pearson Education, Inc.Long Run Costsl EC is equal to 1, MC = ACmCosts increase proportionately with outputmNeither economies nor diseconomies of scalel EC 1 when MC 1 when MC ACmDiseconomies of scalemBoth MC and AC are

31、 rising482005 Pearson Education, Inc.短期成本和长期成本的关系短期成本和长期成本的关系l长期成本曲线是短期成本曲线的包络线492005 Pearson Education, Inc.Long Run Cost withConstant Returns to ScalelThe optimal plant size will depend on the anticipated outputmIf expect to produce q0, then should build smallest plant: AC = $8mIf produce more, li

32、ke q1, AC risesmIf expect to produce q2, middle plant is least costmIf expect to produce q3, largest plant is best502005 Pearson Education, Inc.Long Run Cost with Economiesand Diseconomies of Scale512005 Pearson Education, Inc.l长期成本曲线是短期成本曲线的包络线522005 Pearson Education, Inc.7.5范围经济范围经济l 同时生产两种产品会存在成

33、本上的优势。532005 Pearson Education, Inc.lproduct transformation curves产品转产品转换曲线换曲线l描绘了能以固定数量的投入生产的两种产描绘了能以固定数量的投入生产的两种产出的不同组合。出的不同组合。l产品转换曲线向外弯曲，是因为存在生产产品转换曲线向外弯曲，是因为存在生产的范围经济的范围经济542005 Pearson Education, Inc.Product Transformation CurveNumber of carsNumberof tractorsO1 illustrates a low levelof output

34、. O2 illustratesa higher level of output withtwo times as much labor and capital.Each curve showscombinations of output with a given combination of L & K.O2O1552005 Pearson Education, Inc.Production with Two Outputs Economies of ScopelThe degree of economies of scope (SC) 范围经济程度：mC(q1) is the co

35、st of producing q1mC(q2) is the cost of producing q2mC(q1,q2) is the joint cost of producing both products)qC(q)qC(q)C(q)C(q SC ,212121562005 Pearson Education, Inc.Production with Two Outputs Economies of ScopelWith economies of scope, the joint cost is less than the sum of the individual costslInt

36、erpretation:mIf SC 0 Economies of scopemIf SC 0 and N increases,mL approaches A, and A represents minimum labor input/unit of output after all learning has taken placelThe larger ,mThe more important the learning effect652005 Pearson Education, Inc.The Learning CurveCumulative number ofmachine lots

37、producedHours of laborper machine lot10203040500246810The chart shows a sharp dropin lots to a cumulative amount of20, then small savings at higher levels.Doubling cumulative output causesa 20% reduction in the difference between the input required and minimum attainable input requirement.31. 066200

38、5 Pearson Education, Inc.Dynamic Changes in Costs The Learning Curvel Observations1.New firms may experience a learning curve, not economies of scalelShould increase production of many lots regardless of individual lot size2.Older firms have relatively small gains from learninglShould produce their

39、machines in very large lots to take advantage of lower costs associated with size672005 Pearson Education, Inc.Economies of Scale Versus LearningOutputCost($ per unitof output)AC1BEconomies of ScaleAAC2LearningC682005 Pearson Education, Inc.Predicting Labor Requirements of Producing a Given Output69

40、2005 Pearson Education, Inc.Dynamic Changes in Costs The Learning Curvel From the table, the learning curve implies:1.The labor requirement falls per unit2.Costs will be high at first and then will fall with learning3.After 8 years, the labor requirement will be 0.51 and per unit cost will be half w

41、hat it was in the first year of production702005 Pearson Education, Inc.The Learning Curve in Practicel ScenariomA new firm enters the chemical processing industryl Do they:1.Produce a low level of output and sell at a high price?2.Produce a high level of output and sell at a low price?712005 Pearso

42、n Education, Inc.The Learning Curve in PracticelThe Empirical FindingsmStudy of 37 chemical productslAverage cost fell 5.5% per yearlFor each doubling of plant size, average production costs fall by 11%lFor each doubling of cumulative output, the average cost of production falls by 27%lWhich is more

43、 important, the economies of scale or learning effects?722005 Pearson Education, Inc.The Learning Curve in PracticelOther Empirical FindingsmIn the semiconductor industry, a study of seven generations of DRAM semiconductors from 1974-1992 found learning rates averaged 20%mIn the aircraft industry, t

44、he learning rates are as high as 40%732005 Pearson Education, Inc.The Learning Curve in Practicel Applying Learning Curves1.To determine if it is profitable to enter an industry2.To determine when profits will occur based on plant size and cumulative output742005 Pearson Education, Inc.Estimating an

45、d Predicting CostlEstimates of future costs can be obtained from a cost function, which relates the cost of production to the level of output and other variables that the firm can controllSuppose we wanted to derive the total cost curve for automobile production752005 Pearson Education, Inc.Total Cost Curve for the Automobile IndustryQuantity of CarsVariablecostGeneral MotorsToyotaFordChryslerVolvoHondaNissan762005 Pearson Education, Inc.Estimating and Pre