LECTURE4生产者理论(平狄克,微观经济学-厦门大学,王

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,微观经济学,(平狄克，鲁宾费尔德，第四版),LECTURE 4 生产者理论,1,一、生产,2,生产技术,结合投入品（生产要素）以获得一定产出。,投入品包括劳动、原材料、资本。,生产函数：,在既定技术条件下，每一特定组合的生产要素投入的最高产出，显示在厂商有效运作中的技术可行性。,两要素生产函数：,Q=F(K,L),等产量线：图,PP4,3,Production with Two Variable Inputs (,L,K,),Labor per year,1,2,3,4,1,2,3,4,5,5,Q,1,=,55,The isoquants are derived,from the production,function for output of,of 55, 75, and 90.,A,D,B,Q,2,=,75,Q,3,=,90,C,E,Capital,per year,The Isoquant Map,4,短期,VS,长期,短期：,一种或一种以上的生产要素数量不能变更，被称为固定投入品；,长期：,所有投入品数量都可变更。,5,一种可变投入的生产函数,据图,PP7,随着工人数量增加，产出增加，直到最大值，之后再增加工人数量，产出减少。,劳动平均产出先增后减；,劳动边际产出最初迅速上升，然后逐渐下降，最后变为负值。,6,Production withOne Variable Input (Labor),Labor,per Month,Output,per,Month,60,112,0,2,3,4,5,6,7,8,9,10,1,A,B,C,D,8,10,20,E,0,2,3,4,5,6,7,9,10,1,30,Output,per,Month,Labor,per Month,AP =,slope of line from origin to a point on,TP, lines,b, & c.,MP =,slope of a tangent to any point on the,TP,line, lines a & c.,7,边际回报递减法则,假设：,该可变投入（劳动）的质量恒定；,技术水平恒定。,实际：,当劳动数量较少时，专业化生产导致边际回报递增；,当劳动数量较多时，沟通困难带来的低效率导致边际回报递减。,技术进步可以改变边际回报递减法则。,图,PP9。,8,The Effect ofTechnological Improvement,Labor per,time period,Output,per,time,period,50,100,0,2,3,4,5,6,7,8,9,10,1,A,O,1,C,O,3,O,2,B,Labor productivity,can increase if there,are improvements in,technology, even though,any given production,process exhibits,diminishing returns to,labor.,9,劳动生产率,消费增长只依赖于劳动生产率增长，,而劳动生产率的增长取决于两个因素：,资本存量、技术变迁。,10,两种可变投入的生产函数,就长期而言，劳动（,L,）,和资本（,K,）,都可变，并都遵循报酬递减法则。图,PP12。,11,The Shape of Isoquants,Labor per year,1,2,3,4,1,2,3,4,5,5,In the long run both,labor and capital are,variable and both,experience diminishing,returns.,Q,1,=,55,Q,2,=,75,Q,3,=,90,Capital,per year,A,D,B,C,E,12,两种可变投入的生产函数,边际技术替代率：,等产量线的斜率，反映在保持产出恒定的条件下两种投入品的替代比率。,边际技术替代率递减，因此等产量线凸向原点。,MRTS,与边际产出：,13,Marginal Rate of Technical Substitution,Labor per month,1,2,3,4,1,2,3,4,5,5,Capital,per year,Isoquants are downward,sloping and convex,like indifference,curves.,1,1,1,1,2,1,2/3,1/3,Q,1,=,55,Q,2,=,75,Q,3,=,90,14,完全可替代投入品的生产函数,等产量线上的所有点,MRTS,均相等；,给定产出量，任何投入品组合均可实现。,15,Isoquants When Inputs are Perfectly Substitutable,Labor,per month,Capital,per,month,Q,1,Q,2,Q,3,A,B,C,16,固定比率投入品的生产函数,每一产出要求特定数量的各种投入品。,要提高产出只能同比率提高资本和劳动。,17,Fixed-Proportions Production Function,Labor,per month,Capital,per,month,L,1,K,1,Q,1,Q,2,Q,3,A,B,C,18,规模报酬,衡量厂商规模和其产出之间的关系。,规模报酬递增：等产量线越来越密。,规模报酬恒定：等产量线分布均匀。,规模报酬递减：等产量线越来越稀。,19,Returns to Scale,Labor (hours),Capital,(machine,hours),10,20,30,Increasing Returns:,The isoquants move closer together,5,10,2,4,0,A,20,Returns to Scale,Labor (hours),Capital,(machine,hours),Constant Returns:,Isoquants are equally spaced,10,20,30,15,5,10,2,4,0,A,6,21,Returns to Scale,Labor (hours),Capital,(machine,hours),Decreasing Returns:,Isoquants get further,apart,10,20,30,5,10,2,4,0,A,22,二、生产成本,23,基本概念,生产函数：,生产函数给出投入品和产出之间的关系。,生产成本：,给定生产技术，经理应决定如何生产，而要确定最优的投入,-,产出组合，就应将生产的单位计量转换为货币计量，这就是生产成本。,会计成本,VS,经济成本,会计成本：真实开支,+,固定资本折旧；,经济成本：生产过程中使用的经济资源，包括了机会成本。,24,基本概念,机会成本,沉淀成本：,沉淀成本不应影响厂商决策。,固定成本,VS,可变成本；,固定成本,VS,沉淀成本,边际成本,VS,平均总成本,平均总成本,=,平均固定成本,+,平均可变成本,25,短期成本,报酬递增：,产出相对投入品递增，总成本和可变成本相对产出递减。,报酬递减：,产出相对投入品递减，总成本和可变成本相对产出递增。,较低的边际产出意味着较高的边际成本，反之亦然。,图,PP27-31,26,Cost Curves for a Firm,Output,Cost,($ per,year),100,200,300,400,0,1,2,3,4,5,6,7,8,9,10,11,12,13,VC,Variable cost,increases with,production and,the rate varies with,increasing &,decreasing returns.,TC,Total cost,is the vertical,sum of FC,and VC.,FC,50,Fixed cost does not,vary with output,27,Cost Curves for a Firm,Output (units/yr.),Cost,($ per,unit),25,50,75,100,0,1,2,3,4,5,6,7,8,9,10,11,MC,ATC,AVC,AFC,28,Cost Curves for a Firm,The line drawn from the origin to the tangent of the variable cost curve:,Its slope equals AVC,The slope of a point on VC equals MC,Therefore, MC = AVC at 7 units of output (point,A,),Output,P,100,200,300,400,0,1,2,3,4,5,6,7,8,9,10,11,12,13,FC,VC,A,TC,29,Cost Curves for a Firm,Unit Costs,AFC falls continuously,When MC AVC or MC AVC or MC ATC, AVC & ATC increase,Output (units/yr.),Cost,($ per,unit),25,50,75,100,0,1,2,3,4,5,6,7,8,9,10,11,MC,ATC,AVC,AFC,30,Cost Curves for a Firm,Unit Costs,MC = AVC and ATC at minimum AVC and ATC,Minimum AVC occurs at a lower output than minimum ATC due to FC,Output (units/yr.),Cost,($ per,unit),25,50,75,100,0,1,2,3,4,5,6,7,8,9,10,11,MC,ATC,AVC,AFC,31,长期成本,成本最小化的投入选择,将等成本线与等产量线相结合。,图：,PP33,一种投入品价格变化时的投入替代问题：图,PP34,等产量线、等成本线和生产函数：,因此，成本最小化的投入组合条件（边际相等原则）为：,32,Producing a GivenOutput at Minimum Cost,Labor per year,Capital,per,year,Isocost,C,2,shows quantity,Q,1,can be produced with,combination,K,2,L,2,or,K,3,L,3,.,However, both of these,are higher cost combinations,than,K,1,L,1,.,Q,1,Q,1,is an isoquant,for output,Q,1.,Isocost curve,C,0,shows,all combinations of,K,and,L,that can produce,Q,1,at this,cost level.,C,0,C,1,C,2,C,O,C,1,C,2,are,three,isocost lines,A,K,1,L,1,K,3,L,3,K,2,L,2,33,Input Substitution When an Input Price Change,C,2,This yields a new combination,of,K,and,L,to produce,Q,1,.,Combination,B,is used in place,of combination,A.,The new combination represents,the higher cost of labor relative,to capital and therefore capital,is substituted for labor.,K,2,L,2,B,C,1,K,1,L,1,A,Q,1,If the price of labor,changes, the isocost curve,becomes steeper due to,the change in the slope -,(w/L).,Labor per year,Capital,per,year,34,不同产出水平下的成本最小化,厂商的扩张路径显示了不同产出水平下的成本最小化投入组合选择。图,PP36。,长期成本曲线,VS,短期成本曲线：图,PP37。,35,A Firms Expansion Path,Labor per year,Capital,per,year,Expansion Path,The expansion path illustrates,the least-cost combinations of,labor and capital that can be,used to produce each level of,output in the long-run.,25,50,75,100,150,100,50,150,300,200,A,$2000,Isocost Line,200,Unit,Isoquant,B,$3000,Isocost Line,300,Unit Isoquant,C,36,Long-Run,Expansion,Path,The long-run expansion,path is drawn as before.,The Inflexibility of Short-Run Production,Labor per year,Capital,per,year,L,2,Q,2,K,2,D,C,F,E,Q,1,A,B,L,1,K,1,L,3,P,Short-Run,Expansion,Path,37,长期平均成本（,LAC,）,一般来说厂商的,LAC,经历先规模报酬递增再规模报酬递减，因此,LAC,是一条,U,形曲线。,LAC,和长期边际成本（,LMC,）,有如下关系：,LMC LAC,，,则,LAC,递增；,LMC = LAC,，,此时,LAC,最小。,38,Long-Run Average and Marginal Cost,Output,Cost,($ per unit,of output,LAC,LMC,A,39,规模经济,VS,规模不经济,规模经济：,产出增量大于投入增量；,规模不经济：,产出增量小于投入增量。,规模经济的衡量：,于是我们得到如下关系：,EC, 1: MC ,1: MC AC,，,规模不经济递增。,40,长期成本曲线和短期成本曲线,长期平均成本曲线是短期平均成本曲线的包络线。,41,Long-Run Cost withConstant Returns to Scale,Output,Cost,($ per unit,of output,Q,3,SAC,3,SMC,3,Q,2,SAC,2,SMC,2,LAC =,LMC,With many plant sizes with SAC = $10,the LAC = LMC and is a straight line,Q,1,SAC,1,SMC,1,42,Long-Run Cost with Economiesand Diseconomies of Scale,Output,Cost,($ per unit,of output,SMC,1,SAC,1,SAC,2,SMC,2,LMC,If the output is,Q,1,a manager,would chose the small plant,SAC,1,and SAC $8.,Point,B,is on the LAC because,it is a least cost plant for a,given output.,$10,Q,1,$8,B,A,LAC,SAC,3,SMC,3,43,范围经济,优势：,资本和劳动的联合运用；,管理资源的分享；,劳动技术和机器类型的共用。,产品转换曲线：,厂商应选择两种产品各自的产量，,斜率为负；凹向原点；,PP45,规模经济与范围经济不存在必然关系。,44,Product Transformation Curve,Number of cars,Number,of tractors,O,2,O,1,illustrates a low level,of output.,O,2,illustrates,a higher level of output with,two times as much labor,and capital.,O,1,Each curve shows,combinations of output,with a given combination,of,L & K.,45,范围经济程度,衡量了范围经济带来的成本节约：,SC 0,，,范围经济；,SC R(q),Negative profit,FC + VC ,R(q),MR MC,Indicates higher profit at higher output,0,Cost,Revenue,Profit,($s per year),Output (units per year),R(q),C(q),A,B,q,0,q,*,Marginal Revenue, Marginal Cost,and Profit Maximization,53,Comparing,R(q),and,C(q),Question,: Why is profit negative when output is zero?,Marginal Revenue, Marginal Cost,and Profit Maximization,R(q),0,Cost,Revenue,Profit,$ (per year),Output (units per year),C(q),A,B,q,0,q,*,54,Comparing,R(q),and,C(q),Output levels:,q,0,-,q,*,R,(q) C(q),MR MC,Indicates higher profit at higher output,Profit is increasing,R(q),0,Cost,Revenue,Profit,$ (per year),Output (units per year),C(q),A,B,q,0,q,*,Marginal Revenue, Marginal Cost,and Profit Maximization,55,Comparing,R(q),and,C(q),Output level:,q,*,R,(q) C(q),MR = MC,Profit is maximized,R(q),0,Cost,Revenue,Profit,$ (per year),Output (units per year),C(q),A,B,q,0,q,*,Marginal Revenue, Marginal Cost,and Profit Maximization,56,Question,Why is profit reduced when producing more or less than,q*?,R(q),0,Cost,Revenue,Profit,$ (per year),Output (units per year),C(q),A,B,q,0,q,*,Marginal Revenue, Marginal Cost,and Profit Maximization,57,Comparing,R(q),and,C(q),Output levels beyond,q,*,:,R,(q) C(q),MC MR,Profit is decreasing,Marginal Revenue, Marginal Cost,and Profit Maximization,R(q),0,Cost,Revenue,Profit,$ (per year),Output (units per year),C(q),A,B,q,0,q,*,58,Therefore, it can be said:,Profits are maximized when MC = MR.,Marginal Revenue, Marginal Cost,and Profit Maximization,R(q),0,Cost,Revenue,Profit,$ (per year),Output (units per year),C(q),A,B,q,0,q,*,59,边际收益、边际成本与利润最大化,竞争性厂商：,竞争性厂商是价格接受者，因此其需求曲线与市场需求曲线不同，是一水平直线，图,PP61。,如厂商试图略微提价，则销售量为,0,，,如厂商试图略微降价，则它将发生亏损。,因此，厂商的利润最大化点为,MC(q)=MR=P,，,注意：该公式确定的是产量，价格为市场给定，厂商无法改变。,60,Demand and Marginal Revenue Facedby a Competitive Firm,Output,(bushels),Price,$ per,bushel,Price,$ per,bushel,Output,(millions,of bushels),d,$4,100,200,100,Firm,Industry,D,$4,61,选择短期产量,将产出和成本分析结合需求曲线确定厂商的利润最大化条件及此时的产出量。图,PP63-64。,分析：,MC=MR,，,利润最大化；,PATC,，,厂商盈利，,AVC P ATC,，,厂商负利润，但维持生产（才能使损失最小）；,P AVC ATC,，,厂商应停产。,62,q,0,Lost profit for,q,q, q,*,q,1,q,2,A Competitive Firm Making a Positive Profit,10,20,30,40,Price,($ per,unit),0,1,2,3,4,5,6,7,8,9,10,11,50,60,MC,AVC,ATC,AR=MR=P,Output,q,*,At q,*,: MR = MC,and P ATC,D,A,B,C,q,1,: MR MC,and,q,2,: MC MR,and,q,0,: MC = MR,but,MC falling,63,Would this producer,continue to produce with a loss?,A Competitive Firm Incurring Losses,Price,($ per,unit),Output,AVC,ATC,MC,q,*,P = MR,B,F,C,A,E,D,At,q,*,: MR = MC,and P ATC,Losses =(P- AC) x,q,*,or ABCD,64,选择短期产量,经理的一些成本考虑：,平均可变成本不应用以替代边际成本。,厂商的会计分类账的单独科目可能有两个组成部分，但只有一个部分涉及到边际成本。,在确定边际成本时应计入机会成本。,65,竞争性厂商的短期供给曲线,厂商供给曲线是位于平均可变成本最低点以上的边际成本曲线。,PP67,因报酬递减，因此供给曲线是向上倾斜的。,投入品价格变化，厂商将改变产出水平使其边际成本等于改变后的价格。,PP68。,66,A Competitive FirmsShort-Run Supply Curve,Price,($ per,unit),Output,MC,AVC,ATC,P = AVC,What happens,if P ,，,70,A,D,B,C,Producer,Surplus,Alternatively,VC,is the,sum of,MC,or,ODCq,*,.,R,is,P x q,*,or,OABq,*,.,Producer surplus,=,R - VC,or,ABCD.,Producer Surplus for a Firm,Price,($ per,unit of,output),Output,AVC,MC,0,P,q,*,At,q,*,MC = MR.,Between 0 and,q ,MR MC,for all units,.,71,D,P,*,Q,*,Producer,Surplus,Market producer surplus is,the difference between,P*,and,S,from 0 to,Q,*,.,Producer Surplus for a Market,Price,($ per,unit of,output),Output,S,72,选择长期产量,就长期尺度看，,厂商可以变更其规模（厂房、设备）；,并且自由进出入。,会计利润,VS,经济利润,Accounting profit =,R - wL,Economic profit =,R - wL - rK,rk = opportunity cost of capital,长期竞争性均衡,R wL + rk,，,经济利润为正；,R = wL + rk,，,0,经济利润，厂商获得正常收益率，该产业是竞争性的；,R ,ATC.,Profit is equal to,ABCD.,Output Choice in the Long Run,Price,($ per,unit of,output),Output,P = MR,$40,SAC,SMC,In the long run, the plant size will be,increased and output increased to,q,3,.,Long-run profit,EFGD, short run,profit,ABCD.,q,3,q,2,G,F,$30,LAC,E,LMC,74,q,1,A,B,C,D,Output Choice in the Long Run,Price,($ per,unit of,output),Output,P = MR,$40,SAC,SMC,Question: Is the producer making,a profit after increased output,lowers the price to $30?,q,3,q,2,G,F,$30,LAC,E,LMC,75,选择长期产量,进入和退出：,短期利润产生，厂商的长期反映是增加产量；,较高的利润吸引其他厂商进入该行业；,更多的厂商进入该行业导致供给增加，,市场价格下降，均衡重新实现。,76,S,1,Long-Run Competitive Equilibrium,Output,Output,$,per,unit of,output,$,per,unit of,output,$40,LAC,LMC,D,S,2,P,1,Q,1,q,2,Firm,Industry,$30,Q,2,P,2,Profit attracts firms,Supply increases until profit = 0,77,长期竞争性均衡,均衡：,所有厂商都达到利润最大化，,MC = MR,所有厂商经济利润都为,0,，因此没有哪个厂商有动力进入或退出该行业，,P = LAC,，,Profit = 0,均衡市场价格，市场供给等于市场需求。,问题：,如厂商成本相等，试分析当,P LAC,时市场将如何调整；如厂商成本不相等时呢？,78,经济租,投入品的经济租就是投入品的机会成本；,如投入品的机会成本未计入成本，则就长期尺度看厂商将体现为正利润。,长期厂商剩余：,一个厂商的厂商剩余由它的稀缺的投入要素带来的经济租构成。,79,Firms Earn Zero Profit in Long-Run Equilibrium,Ticket,Price,Season Tickets,Sales (millions),LAC,$7,1.0,A baseball team,in a moderate-sized city,sells enough,tickets so that price,is equal to marginal,and average cost,(profit = 0).,LMC,80,1.3,$10,Economic Rent,Ticket,Price,$7,LAC,A team with the same,cost in a larger city,sells tickets for $10.,Firms Earn Zero Profit in Long-Run Equilibrium,Season Tickets,Sales (millions),LMC,81,行业的长期供给曲线,假设：,所有厂商都可自由获得生产技术,产出的增加不来自发明创造，而是增加投入品；,投入品市场不因行业的扩张或收缩而变更。,不同行业的长期供给曲线：,成本恒定行业，长期供给曲线是一条水平线，价格等于长期最小平均成本。,成本递增行业，长期供给曲线向上倾斜，但只有价格高到可以弥补增加的投入成本时行业才能有更多的产出。,成本递减行业，长期供给曲线向下倾斜,。,82,A,P,1,AC,P,1,MC,q,1,D,1,S,1,Q,1,C,D,2,P,2,P,2,q,2,B,S,2,Q,2,Economic profits attract new,firms. Supply increases to,S,2,and,the market returns to long-run,equilibrium.,Long-Run Supply in aConstant-Cost Industry,Output,Output,$,per,unit of,output,$,per,unit of,output,S,L,Q,1,increase to,Q,2,.,Long-run supply =,S,L,= LRAC.,Change in output has no impact on,input cost.,83,Long-Run Supply in anIncreasing-Cost Industry,Output,Output,$,per,unit of,output,$,per,unit of,output,S,1,D,1,P,1,LAC,1,P,1,SMC,1,q,1,Q,1,A,S,L,P,3,SMC,2,Due to the increase,in input prices, long-run,equilibrium occurs at,a higher price.,LAC,2,B,S,2,P,3,Q,3,q,2,P,2,P,2,D,1,Q,2,84,S,2,B,S,L,P,3,Q,3,SMC,2,P,3,LAC,2,Due to the decrease,in input prices, long-run,equilibrium occurs at,a lower price.,Long-Run Supply in anDecreasing-Cost Industry,Output,Output,$,per,unit of,output,$,per,unit of,output,P,1,P,1,SMC,1,A,D,1,S,1,Q,1,q,1,LAC,1,Q,2,q,2,P,2,P,2,D,2,85,税收效应,对厂商的效应，PP87，,对行业的效应，PP88。,86,Effect of an Output Tax on a Competitive Firms Output,Price,($ per,unit of,output),Output,AVC,1,MC,1,P,1,q,1,The firm will,reduce output to,the point at which,the marginal cost,plus the tax equals,the price.,q,2,t,MC,2,= MC,1,+ tax,AVC,2,An output tax,raises the firms,marginal cost by the,amount of the tax.,87,Effect of an OutputTax on Industry Output,Price,($ per,unit of,output),Output,D,P,1,S,1,Q,1,P,2,Q,2,S,2,= S,1,+ t,t,Tax shifts,S,1,to,S,2,and,output falls to,Q,2,.,Price,increases to,P,2,.,88,长期供给弹性,恒定成本行业：,长期成本曲线是一水平线，长期供给弹性无穷大；投入品可方便地获得,。,成本递增行业：,长期成本曲线向上倾斜，（斜率）长期供给弹性为正，大小取决于投入品成本的增长率。,长期供给弹性一般大于短期供给弹性。,89,