1、成本分析第7章成本的经济分析7.1短期The short run:The period in which firms can adjust production only by changing variable factors such as materials and labor but cannot change fixed factors such as capital.固定成本The cost related to fixed factors is called fixed cost(固定成本，不变成本固定成本，不变成本).A firms fixed costs,sometimes
2、called“overhead”(企业一般管理费用企业一般管理费用)or“sunk costs”(沉没成本沉没成本),must be paid even if the firm produces no output,and they will not change if output changes.变动成本The cost related to variable factors is called variable cost(变动成本，可变成变动成本，可变成本本).Variable costs are those which vary as output changes.By definit
3、ion,VC begins at zero when q is zero.总成本是可达到的最小成本Total cost represents the lowest total dollar expense needed to produce each level of output q.说明：说明：与生产函数的处理类似，总成本与生产函数的处理类似，总成本也是指给定产量时的最小成本，目的是也是指给定产量时的最小成本，目的是为了让函数关系具有唯一性。为了让函数关系具有唯一性。Totalcostin short run:in long run:TotalcostVariablecost=Fixedc
4、ostVariablecost+(1)(2)(3)(4)QuantityFixed costVariable costTotal cost=(2)+(3)qFC($)VC($)TC($)05505515530852555511035575130455105160555155210655225280边际成本The concept of marginal cost is one of the most essential in microeconomics.Marginal cost(MC)denotes the extra or additional cost of producing 1 ex
5、tra unit of output.For an airline flying planes with empty seats,the added cost of another passenger is quite low.But on a hot summer day,when everyones conditioners are running,the added electric power comes at a high marginal cost.边际成本的计算(1)(2)(3)OutputTotal costMarginal costQTC($)MC($)05518521103
6、130416052103025203050利用变动成本计算边际成本(1)(2)(3)OutputVariable costMarginal costQVC($)MC($)00130255375410551553025203050MC=TCq+1 TCq =(VCq+1FC)(VCqFC)=VCq+1 VCq数学推导为什么可以用变动成本来计算边际成本：为什么可以用变动成本来计算边际成本：总成本和边际成本的关系OutputTotal costOutputMarginal cost平均成本Average cost(or unit cost)=total costoutput=TCq=ACAverag
7、efixed cost=fixed costoutput=FCq=AFCAveragevariable cost=variable costoutput=VCq=AVC总成本、固定成本和变动成本Total costVariable costFixed costQuantityCost平均成本和边际成本QuantityAverage and marginal costMCACAVCAFC平均成本最小平均成本最小平均变动成本最小平均变动成本最小平均成本与边际成本的关系成本成本产量产量边际成本边际成本平均成本平均成本平均成本最低点平均成本最低点边际成本曲边际成本曲线自下而上线自下而上穿越平均成穿越平
8、均成本曲线的最本曲线的最低点。低点。平均成本边际成本成本成本产量产量边际成本边际成本平均成本平均成本边际成本边际成本平均成本平均成本,平平均成本随着均成本随着产量增加而产量增加而向下。向下。16元元2212元元平均成本边际成本成本成本产量产量边际成本边际成本平均成本平均成本17元元边际成本边际成本 平均成本平均成本,平平均成本随着均成本随着产量增加而产量增加而向上。向上。23元元50边际成本和平均成本的关系ACq+1=ACqqMCq1=ACq(q1)MCACqq1=ACqMCACqq1小结QuantityAC and MC=ACqMCACqq1ACq+1AC边际成本和平均变动成本的关系AVCq
9、+1=AVCqqMCq1=AVCq(q1)MCAVCqq1=AVCqMCAVCqq1小结QuantityAC and MC=AVCqMCAVCqq1AVCq+1AVC斜率和边际成本的关系Tangent lineTotal cost curve1 unit of outputMarginal costaaTCMCQ产量与成本之间的联系The cost curve for a firm depends very closely on the prices of inputs and the firms production function.If you know factor prices an
10、d the production function,you can calculate the cost curve.(1)(2)(3)(4)(5)(6)OutputLandLaborRentWageTotal cost(tons)(acres)(workers)($/acre)($/worker)($)01005.555511065.55?210115.55110310155.55130410215.55160510315.55?610455.55280710635.55370810855.5548085210报酬递减和U形成本曲线LaborMarginal product of labor
11、Marginal costOutputABDABDMCACIn the short run:最小成本规则To a given output:Marginal product of input A APrice of input A A=Marginal product of input B BPrice of input B B=等边际原理BBAAMPPMPP1$1$This gives you the marginal product per dollar of output.替代规则If the price of one factor falls while all other facto
12、r prices remain the same,firms will profit by substituting the now-cheaper factor for all the other factors.MP of LaborPrice of Labor=MP of CapitalPrice of Capital背景知识在资本主义由工场手工业向大机器生产过渡的历史时期，由于机器操作的简单性，女工、童工加入劳动行列，劳动供给增加。与此同时，大机器生产要求相对较多的资本，资本的供给相对稀缺。这是导致工人当时生活贫困的主要原因。当资本不断积累，而生产又要求较为复杂的劳动技能时，在要素市场
13、上，资本不可能总是处于有利的竞争地位。短期成本与长期成本的关系成本成本产量产量长期平均成本长期平均成本1 亩地亩地2 亩地亩地4 亩地亩地3 亩地亩地1 亩地亩地更有利更有利2 亩地亩地更有利更有利3 亩地亩地更有利更有利4 亩地亩地更有利更有利规模经济与规模不经济成本成本产量产量长期平均成本长期平均成本规模经济规模经济规模不经济规模不经济经济成本和企业会计7.2经济成本和会计成本经济成本经济成本（economic cost）：投入生产）：投入生产的所有资源的机会成本。的所有资源的机会成本。会计成本会计成本（accounting cost）：按照会计）：按照会计规则计算的成本规则计算的成本在会
14、计帐面上显示出来的经济成本称为在会计帐面上显示出来的经济成本称为外显（显性）成本外显（显性）成本（explicit costs），在），在会计帐面上不能显示出来的经济成本称会计帐面上不能显示出来的经济成本称为为内含（隐性）成本内含（隐性）成本（implicit costs）。）。经济利润经济成本经济成本 =外显成本外显成本 +内含成本内含成本 =机会成本机会成本经济利润经济利润 =销售收入销售收入 经济成本经济成本经济利润是计入了所有使用的资源代价经济利润是计入了所有使用的资源代价后的纯收益。后的纯收益。一个体饭馆业主使用自己的一个体饭馆业主使用自己的店面，店面，1年盈利年盈利3万元，这个万元
15、，这个3万元称之为会计利润。万元称之为会计利润。若不开饭馆，在所有可选工作中若不开饭馆，在所有可选工作中最高可赚得最高可赚得2万元，人力的经济成万元，人力的经济成本就是本就是2万元。如果店面用于出租万元。如果店面用于出租可以获得可以获得1.5万元租金，那么店面万元租金，那么店面的经济成本就是的经济成本就是1.5 万元。万元。考虑到经济成本后，这个个体饭馆业主的经考虑到经济成本后，这个个体饭馆业主的经济利润为济利润为0.5 万元。万元。收益表(1)Net sales$250,000Less cost of goods sold:(2)Materials$50,000(3)Labor cost90
16、,000(4)Miscellaneous operating costs10,000(5)Less overhead costs:(6)Selling and administrative costs15,000(7)Rent for building5,000(8)Depreciation15,000(9)Operating expenses$185,000185,000(10)Net operating income$65,000收益表(10)Net operating income$65,000Less:(11)interest charges on equipment loan6,00
17、0(12)State and local taxes4,000(13)Net income before income taxes$55,000(14)Less:Corporation income taxes18,000(15)Net income(or profit)after taxes$37,000(16)Less:Dividends paid on common stock15,000(17)Addition or retained earnings$22,000折旧$10,000$10,000$10,000$10,000$10,000$10,000$10,000$10,000$10
18、,000$10,000The depreciation is taken in annual accounting charges over the assets accounting lifetimedepreciation=the capital goods historical cost or purchase price.Depreciation=the annual cost of a capital input that a company actually owns itself.资产负债表AssetsLiabilities and net worthLiabilitiesCur
19、rent assets:Current liabilities:Cash$20,000 Accounts payable$20,000 Inventory80,000 Notes payable30,000Fixed assets:Long-term liabilities:Equipment150,000 Bonds payable100,000 Buildings100,000 Net worthStockholders equity:_ Common stock200,000Total$350,000 Total$350,000关于资产负债表The income statement me
20、asures the flows into and out of the firm,while the balance sheet measures the stocks of assets and liabilities at the end of the accounting year.A balance sheet must always balance:Total assets=total liabilities+net worth例子Suppose total assets are down$40,000;liabilities remain unchanged.This means
21、 total net worth has decreased by$40,000,and should write net worth down from the previous$200,000 to only$160,000.AssetsLiabilities and net worthLiabilities$40,000Net worthCommon stock$40,000会计惯例The value placed on almost every item reflects its historical costs.说明“收益表收益表”是描述一指定会计时间段中是描述一指定会计时间段中货币
22、流入和流出企业的情况。货币流入和流出企业的情况。“资产负债表资产负债表”是指在某一特定的会计是指在某一特定的会计时刻，企业的资产、负债和所有者权益时刻，企业的资产、负债和所有者权益状况。状况。总之，总之，“收益表收益表”是对一时段而言的，是对一时段而言的，“资产负债表资产负债表”是对一时点而言的。是对一时点而言的。机会成本7.3机会成本问题市场价格与机会成本$25.02(Market price)$25.01(Opportunity cost)$24.98生产、成本理论和企业决策附录生产函数的数值例子Q=100 2LAQ=output;L=labor;A=land.The production
23、 function is a constant-returns-to-scale production function,a special case of the Cobb-Douglas production function.3464906006927758463164485486327057752824004905646326922453464234905486002002823464004484901412002452823163466543210123456Constant returns to scaleLaborLand34649060069277584631644854863
24、27057752824004905646326922453464234905486002002823464004484901412002452823163466543210123456Diminishing marginal product of laborLaborLand82645448423464906006927758463164485486327057752824004905646326922453464234905486002002823464004484901412002452823163466543210123456Diminishing marginal product of
25、 landLaborLand525867771013464906006927758463164485486327057752824004905646326922453464234905486002002823464004484901412002452823163466543210123456LaborLandABCDA、B、C和和D点的产点的产量相等。量相等。给定产量的最低要素成本组合(1)(2)(3)(4)Input CombinationTotal costTotal costLaborLandPL=$2PL=$2LAPA=$3PA=$1A1620?B2313?C3212?D6115?给定
26、产量的最低要素成本组合(1)(2)(3)(4)Input CombinationTotal costTotal costLaborLandPL=$2PL=$2LAPA=$3PA=$1A16208B23137C32128D611513等产量曲线3464906006927758463164485486327057752824004905646326922453464234905486002002823464004484901412002452823163466543210123456LaborLand654321Land0123456LaborABCDqEqual-product curve or
27、 isoquantThere are an infinite number of equal-product contour lines(等值线等值线)in the map.654321Land0123456LaborABDqCALMACLNMN:AMPA=L MPLALMPMPLA替代率等成本线654321Land012345678LaborLabor price=$2,Land price=$3TC=$3TC=$6TC=$9TC=$12TC=$15TC=$18equal-cost Line:TCqPqPAALL654321Land012345678LaborTC=$3TC=$6TC=$9TC=$12TC=$15equal-cost Line:TCqPqPAALLALAPA=L PLALPPLA替代率最低成本投入组合654321Land012345678LaborTC=$3TC=$6TC=$9TC=$12ABCDALMPMPLAALPPLAALALPPMPMP最低成本条件ALALPPMPMPAALLPMPPMP说明等产量线方法一般用于企业的长期行为分析，因为对于长期来说，所有的生产要素都可以改变，所以可以在等产量线上进行选择。对于短期分析而言，按惯例一般不使用等产量线分析方法。End Of Lesson
