第七微观经济学供给与需求的市场力量

供给与需求的市场力量©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.1当前1页，总共53页。市场与竞争供给与需求经济学家们最常使用的词汇使市场经济运行的力量买者与卖者行为，以及他们相互之间的影响©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.2当前2页，总共53页。市场与竞争市场由某种商品或服务的买者与卖者组成的一个群体买方群体决定产品的需求卖方群体决定产品的供给©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.3当前3页，总共53页。市场与竞争市场采取多种形式市场组织健全·许多农产品市场并没有什么组织·某镇上冰淇淋市场©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.4当前4页，总共53页。市场与竞争竞争市场市场中有许多买者和许多卖者每一个对市场价格的影响可以忽略不计价格和数量由买卖双方决定它们在市场上相互作用©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.5当前5页，总共53页。市场与竞争完全竞争市场提供出售的货物都是完全相同的买者和卖者是如此众多买方或卖方对市场价格有任何影响价格接受者市场价格买者可以购买他们想要的一切卖者可以出售他们想出售的一切©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.6当前6页，总共53页。市场与竞争垄断市场上唯一的卖方价格的决定其他的市场在完全竞争与垄断之间©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.7当前7页，总共53页。需求

需求量买者愿意并且能够购买一种物品的数量需求法则其他条件不变当一种商品的价格上升时，商品的需求数量下降的观点当价格下降时，需求量上升©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.8当前8页，总共53页。需求

需求一种商品的价格和需求量之间的关系需求表：是一张表需求曲线：是一张图价格在垂直轴水平轴的数量个人需求个人对产品的需求©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.9当前9页，总共53页。图1©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.Catherine需求曲线和需求曲线需求曲线需求表是显示每个价格水平下的需求量的表。根据需求表画出需求曲线图表示一种物品的需求量如何随其价格变动而变动。较低的价格增加了需求量，因此需求曲线向下倾斜。冰淇淋的价格冰淇淋的数量$0.000.501.001.502.002.503.0012cones10864200121011912345678冰淇淋的数量$3.002.502.001.501.000.50冰淇淋的价格1.价格下降...2....需求量上升10当前10页，总共53页。需求

市场需求为一种商品或服务的所有个人需求总和市场需求曲线水平的个体需求曲线一种商品的总需求量的变化商品价格各不一样其他条件不变©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.11当前11页，总共53页。图2©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.作为个人需求之和的市场需求一个市场的需求量是所有买者在每一价格水平下水平下的需求量总和。因此，可以通过把个人需求曲线水平相加而得出市场需求曲线。在价格2美元时，Catherine的需求量是4个冰淇淋蛋卷，Nicholas的需求量是3个冰淇淋蛋卷。在这一价格水平下，在市场上的需求量是7个冰淇淋蛋卷。12当前12页，总共53页。图2©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.作为个人需求之和的市场需求DCatherine0121011912345678冰淇淋的数量$3.002.502.001.501.000.50冰淇淋的价格Catherine的需求DNicholas01234567冰淇淋的数量$3.002.502.001.501.000.50冰淇淋的价格Nicholas的需求+=DMarket018246810121416冰淇淋的数量$3.002.502.001.501.000.50冰淇淋的价格市场需求13当前13页，总共53页。需求

需求曲线的移动需求量的上升每一价格水平下的变化，增加的的数量需求曲线向右移动需求量的减少每一价格水平下的变化要减少需求量的数量需求曲线向左移动©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.14当前14页，总共53页。图3©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.需求曲线的移动冰淇淋的价格冰淇淋的数量

0需求曲线,D1需求曲线,D3需求曲线,D2需求上升需求减少既定价格水平下，任何使买者想购买的数量都增加的变动都会使需求曲线向右移动。既定价格水平下，任何使买者想购买的数量都减少的变动都会使需求曲线向左移动。15当前15页，总共53页。需求

可以改变需求曲线的变量收入相关物品价格爱好预期买者数量©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.16当前16页，总共53页。需求

收入正常品其他条件不变收入的增加导致了需求的增加低档品其他条件不变收入的增加导致需求的减少©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.17当前17页，总共53页。需求

相关物品价格替代品，两种物品一种物品价格的上升导致另一种物品需求增加互补品，两种物品一种物品价格的上升导致另一种物品需求减少©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.18当前18页，总共53页。需求

爱好爱好变化：改变需求对未来的预期预期收入增加增加目前的需求期待更高的价格增加目前的需求买者数量，增加市场需求增加©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.19当前19页，总共53页。表1©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.影响买者的变量这张表列出了可以影响消费者选择购买多少某种物品的变量。要注意的是价格所起的特殊作用：价格变动表现为沿着需求曲线的变动，而其他任何一个变量的变动将使需求曲线移动。20当前20页，总共53页。减少香烟需求的两种方法使香烟和其他烟草产品的需求曲线移动试着提高香烟的价格©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.21“什么是制止这种行为最好的方法？”当前21页，总共53页。减少香烟需求的两种方法香烟和其他烟草产品的需求曲线的移动

公共服务公告香烟包装上的强制性健康警告在电视上禁止吸烟广告若成功需求曲线向左移动©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.22当前22页，总共53页。减少香烟需求的两种方法试着提高香烟的价格对制造商征税：更高的价格沿需求曲线运动10%↑

价格

→4%↓

吸烟量青少年:10%↑

价格→12%↓

吸烟量对香烟需求与大麻需求互补品©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.23当前23页，总共53页。图4©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.需求曲线移动与沿着需求曲线的变动PriceofCigarettes,perPackNumberofCigarettesSmokedperDay0D1D21020$2.00BA(a)需求曲线的转变24如果香烟包装上的警示能说服吸烟者少吸烟，那么香烟的需求曲线就向左边移动。在（a）幅中，需求曲线从D1移动到D2。在价格为每包2美元时，需求量由每天20支减少到10支，如图中从A点到B点所示。与此相比，如果税收提高香烟的价格，需求曲线没有移动，而是变动到其上另一点。在（b）幅中，当价格从2美元上升到4美元，需求量从每天20支烟减少到12支烟，如图中是从A点移动到C点所示。当前24页，总共53页。供给

供给量卖方愿意并且能够出售的一个物品的数量供给法则其他条件不变当一个物品的价格上升时，供给的数量也上升了当价格下跌时，供给量下降©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.25当前25页，总共53页。供给

供给商品的价格和供给量之间的关系供给表：是一张表供给曲线：是一张图价格在纵轴水平轴是供给的数量个人供给卖方个人的供给©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.26当前26页，总共53页。图5©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.Ben的供给计划和供给曲线冰淇淋的价格冰淇淋的供给量$0.000.501.001.502.002.503.000012345Supplycurve供给表是显示在每一个价格水平下的供给量的表格。根据供给表画出供给曲线图表示一种物品的供给量如何随其价格变动而变动。由于价格越高，供给量越多，所以，供给曲线向右上方倾斜。0121011912345678冰淇淋的数量$3.002.502.001.501.000.50冰淇淋的价格1.价格的上升...2....increasesquantityofconessupplied.27当前27页，总共53页。供给

市场供给为一种商品或服务所有卖方的供给量总和市场供给曲线个人供给曲线的水平总和一种商品的总供给量的变化商品的价格各不一样影响供给者出售的所有其他因素都保持不变©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.28当前28页，总共53页。图6©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.市场供给作为个人用品的总和市场供给量是在每种价格水平下所有卖者的供给量之和。因此，可以通过水平地相加个人供给曲线的出市场供给曲线。在价格为2美元时，Ben供给3个冰淇淋蛋卷，而Jerry供给4个冰淇淋蛋卷。在这一价格水平下，市场供给量是7个冰淇淋蛋卷。29当前29页，总共53页。图6©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.市场供给作为个人用品的总和SBen01234567QuantityofIce-CreamCones$3.002.502.001.501.000.50冰淇淋的价格本的供给SJerry01234567QuantityofIce-CreamCones$3.002.502.001.501.000.50冰淇淋的价格杰瑞的供给+=SMarket018246810121416QuantityofIce-CreamCones$3.002.502.001.501.000.50冰淇淋的价格市场供给30当前30页，总共53页。供给

供给变动供给增加每一价格水平下供给数量增加的任何一种变化供给曲线向右移动供给减少每一价格水平下供给数量减少的任何一种变化供给曲线向左移动©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.31当前31页，总共53页。图7©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.供给曲线的变化冰淇淋价格

冰淇淋数量

0供给曲线,S1供给曲线,S3供给曲线,S2供给右移

供给左移使任何既定价格水平下卖者愿意生产的数量都增加的任何一种变动，都会使供给曲线向右移动。使任何既定价格水平下卖者愿意生产的数量都减少的任何一种变动，都会使供给曲线向左移动。32当前32页，总共53页。供给

能改变供给曲线的变量投入品价格技术预期卖者的数量©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.33当前33页，总共53页。供给

投入品价格供给与投入品价格呈负相关价格上升：使供给减少技术技术进步：使供给增加©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.34当前34页，总共53页。供给

关于未来的预期影响现在的供给预期价格上升减少现在的供给卖者数量，增加市场供给增加©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.35当前35页，总共53页。表2©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.影响卖者的变量该表列出了可以影响生产者选择出售多少某种物品的变量。要注意价格所起的特殊作用：价格变动表现为沿着供给曲线的变动，而其他任何一个变量的变动都将使供给曲线移动。36当前36页，总共53页。供给与需求的结合均衡

各种力量达到平衡一种市场价格已经达到的水平供给量=需求量供需曲线相交©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.37当前37页，总共53页。供给与需求的结合均衡价格供给量和需求量市场出清价格均衡数量

均衡价格的供给量和需求量©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.38当前38页，总共53页。图8©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.供给与需求的均衡供给0121011912345678冰淇淋的数量$3.002.502.001.501.000.50冰淇淋的价格均衡需求均衡价格均衡数量均衡出现在供给和需求曲线相交的那一点。在均衡价格时，供给量等于需求量。这里的均衡价格是2美元：在这一价格水平下，供给量是7个冰淇淋蛋卷，需求量也是7个冰淇淋蛋卷。39当前39页，总共53页。供给与需求的结合剩余供给量＞需求量供给过剩价格下降的压力沿着需求和供给曲线运动需求量的增加供给减少©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.40当前40页，总共53页。供给与需求的结合短缺供给量＞供给量超额需求价格上升压力沿着需求和供给曲线运动减少需求量供给量的增加©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.41当前41页，总共53页。图9©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.市场不处于均衡时冰淇淋的价格冰淇淋的数量0Demand7$2.50(a)供给过量2.00SupplySurplus4Quantitydemanded10Quantitysupplied冰淇淋的价格SplyShortage4Quantitsupplied10Quantdemanded42在（a）幅中，存在着剩余。因为2.5美元的市场价格高于均衡价格，供给量（10个）超过需求量（4个）。供给商试图通过削减冰淇淋蛋卷的价格来增加销售量，这将会使价格向均衡水平移动。在（b）幅中，存在短缺。因为1.5美元的市场价格低于均衡价格，需求量（10个）超过供给量（4个）。由于太多的买者在追逐太少的商品，供给商可以通过提高价格来利用这一优势。因此，在这两种情况下，价格调整移动市场对供需平衡当前42页，总共53页。供给与需求的结合供给与需求法则任何商品的价格调整使供给量和需求量的数量要达到平衡大多数市场中盈余和短缺是暂时的©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.43当前43页，总共53页。供给与需求的结合分析平衡变化的三个步骤决定事件是否在某些情况下，改变供给曲线，需求曲线，或在某些情况下，这两个曲线决定曲线向右或向左移动使用供求关系图比较初始和新的均衡均衡价格和数量的影响©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.44当前44页，总共53页。供给与需求的结合由于需求的变动市场均衡的变化夏天，很热的天气冰淇淋市场的影响？热天气：改变需求曲线（爱好）需求曲线向右边移动均衡价格；均衡数量©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.45当前45页，总共53页。图10©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.需求增长如何影响均衡SupplyNewequilibriumD2使任何一种既定价格水平下需求量增加的事件使需求曲线向右移动。均衡价格与均衡数量都上升了。在本例中，异常炎热的夏季使买者需要更多的冰淇淋。需求曲线从D1移动到D2，导致均衡价格从2美元上升到2.5美元，均衡数量从7个上升到10个。冰淇淋的价格冰淇淋的数量07$2.502.0010D1Initialequilibrium1.Hotweatherincreasesthedemandforicecream...2.…resultinginahigherprice...3.…andahigherquantitysold.46当前46页，总共53页。供给与需求的结合沿曲线移动与运动供给曲线的变动·供给变化沿固定供给曲线变动·供给量的变化需求曲线移动·需求变化沿固定需求曲线变动·需求量的变化©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.47当前47页，总共53页。供给与需求的结合供给变动引起的市场均衡变化在一个夏天，一场飓风摧毁了一部分甘蔗作物：更高的糖价格冰淇淋市场的影响？糖的价格变化：供给曲线供给曲线：向左移动均衡价格；均衡量©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorserviceorotherwiseonapassword-protectedwebsiteforclassroomuse.48当前48页，总共53页。图11©2015CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart,exceptforuseaspermittedinalicensedistributedwithacertainproductorse