经济学原理曼昆第04章课件

1、2 SUPPLY AND DEMAND I: HOW MARKETS WORK供给供给与需求（与需求（I）：）：市场如何运行市场如何运行The Market Forces of Supply and Demand供给与需求的市场力量供给与需求的市场力量Chapter 4Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.The Market Forces of Supply and DemanduSupply and demand are the two words that economists use

2、 most often.uSupply and demand are the forces that make market economies work.uModern microeconomics is about supply, demand, and market equilibrium.Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.供给与需求的市场力量供给与需求的市场力量n供给供给和和需求需求是经济学家最常用的是经济学家最常用的两个词。两个词。n供给供给和和需求需求是让市场经济运行的是让市

3、场经济运行的力量。力量。n现代微观经济学就是关于供给、现代微观经济学就是关于供给、需求和市场均衡的学科。需求和市场均衡的学科。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.MarketsuA market is a group of buyers and sellers of a particular good or service. uThe terms supply and demand refer to the behavior of people . . . as they interact

4、 with one another in markets. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.市场市场u市场市场 是指某种物品或劳务的一群是指某种物品或劳务的一群买者与卖者的集合。买者与卖者的集合。 u供给与需求这两个术语是指人们供给与需求这两个术语是指人们在在市场市场上相互交易时的行为。上相互交易时的行为。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Markets and competit

5、ion 市场与竞争市场与竞争u Buyers determine demand. 买者决定买者决定需求需求u Sellers determine supply. 卖者决定卖者决定供给供给Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.A Competitive Market 竞争市场竞争市场 A competitive market is a market in which there are many buyers and sellers so that each has a negligible

6、impact on the market price 竞争市场竞争市场有很多买者和卖者的有很多买者和卖者的市场，所以每一个买者或卖者对市市场，所以每一个买者或卖者对市场价格的影响都可以忽略不计。场价格的影响都可以忽略不计。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Competition: Perfect and OtherwiseuProducts are the sameuNumerous buyers and sellers so that each has no influence ove

7、r priceuBuyers and Sellers are price takersPerfect CompetitionHarcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.竞争竞争: 完全及其它完全及其它u产品是完全相同的。产品是完全相同的。u买者和卖者如此之多，以至于没有买者和卖者如此之多，以至于没有一个买者或卖者可以影响价格。一个买者或卖者可以影响价格。u买者和卖者都是价格接受者。买者和卖者都是价格接受者。完全竞争完全竞争Harcourt, Inc. items and derived items

8、 copyright 2001 by Harcourt, Inc.Competition: Perfect and OtherwiseuMonopolyuOne seller, and seller controls priceuOligopolyuFew sellersuNot always aggressive competitionHarcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.竞争竞争: 完全及其它完全及其它u垄断垄断u一个卖者，卖者决定价格一个卖者，卖者决定价格。u寡头寡头u少数几个卖者。少

9、数几个卖者。u并不总是主动地进行竞争。并不总是主动地进行竞争。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Competition: Perfect and OtherwiseuMonopolistic CompetitionuMany sellersuSlightly differentiated productsuEach seller may set price for its own productHarcourt, Inc. items and derived items copyrigh

10、t 2001 by Harcourt, Inc.竞争竞争: 完全及其它完全及其它u垄断竞争垄断竞争u许多卖者许多卖者u略有差异的产品略有差异的产品u每个卖者都有决定自己产品价每个卖者都有决定自己产品价格的能力格的能力Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Demand 需求需求Quantity demanded is the amount of a good that buyers are willing and able to purchase. 需求量需求量是指买者愿意而且能够购是指买者愿

11、意而且能够购买的一种物品或劳务的数量。买的一种物品或劳务的数量。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Law of Demand 需求规律需求规律The law of demand states that there is an inverse relationship between price and quantity demanded. 需求规律需求规律认为，价格与需求量之间认为，价格与需求量之间的关系是负关系。的关系是负关系。Harcourt, Inc. items and deri

12、ved items copyright 2001 by Harcourt, Inc.Demand Schedule 需求表需求表 The demand schedule is a table that shows the relationship between the price of the good and the quantity demanded. 需求表需求表 表示一种物品的价格表示一种物品的价格与需求量之间关系的表格。与需求量之间关系的表格。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc

13、.Catherines Demand Schedule 凯瑟琳的需求表凯瑟琳的需求表Price 价格 Quantity 数量 $0.00 12 0.50 10 1.00 8 1.50 6 2.00 4 2.50 2 3.00 0 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Demand Curve 需求曲线需求曲线The demand curve is the downward-sloping line relating price to quantity demanded. 需求曲线需求曲线把价

14、格与需求量联系在把价格与需求量联系在一起的向右下方倾斜的曲线。一起的向右下方倾斜的曲线。Figure 1 Catherines Demand Schedule and Demand CurvePrice ofIce-Cream Cone02.502.001.501.000.50123456789 10 11Quantity ofIce-Cream Cones$3.00121. A decrease in price .2. . increases quantity of cones demanded.图图1. Catherine的需求表和需求曲线的需求表和需求曲线冰激凌蛋卷冰激凌蛋卷的价格的价

15、格02.502.001.501.000.50123456789 10 11冰激凌蛋卷冰激凌蛋卷需求量需求量$3.00121. 价格下降 2. . 蛋卷的需求量上升。价格 需求量 $0.00 12 0.50 10 1.00 8 1.50 6 2.00 4 2.50 2 3.00 0 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Market Demand versus Individual DemanduMarket demand refers to the sum of all individual

16、 demands for a particular good or service.uGraphically, individual demand curves are summed horizontally to obtain the market demand curve.Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.市场需求市场需求u市场需求市场需求 是指所有个人对某种物是指所有个人对某种物品或劳务需求的总和。品或劳务需求的总和。u从图形上看从图形上看, 把个人需求曲线把个人需求曲线水平水平相

17、加，就得出了市场需求曲线。相加，就得出了市场需求曲线。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Change in Quantity Demanded versus Change in DemandChange in Quantity DemandeduMovement along the demand curve.uCaused by a change in the price of the product.Harcourt, Inc. items and derived items copy

18、right 2001 by Harcourt, Inc.需求量的变化与需求的变化需求量的变化与需求的变化需求量需求量的变化的变化u沿着需求曲线移动沿着需求曲线移动。u是由于产品价格变动引起的。是由于产品价格变动引起的。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.0DPrice of Ice-Cream ConesQuantity of Ice-Cream ConesA tax that raises the price of ice-cream cones results in a movemen

19、t along the demand curve.AB81.00$2.004Changes in Quantity DemandedHarcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.0D冰激凌冰激凌蛋卷蛋卷的的价格价格冰激凌冰激凌蛋卷的消费量蛋卷的消费量提高冰激凌蛋卷价格的税收引起沿着需求曲线的移动AB81.00$2.004需求量的变化需求量的变化Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Shifts i

20、n the Demand CurveuConsumer incomeuPrices of related goodsuTastesuExpectationsuNumber of buyersHarcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.需求曲线的移动需求曲线的移动u消费者收入消费者收入u相关产品价格相关产品价格u嗜好嗜好u预期预期u买者数量买者数量Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Shifts

21、 in the Demand CurveChange in DemanduA shift in the demand curve, either to the left or right.uCaused by a change in a determinant other than the price.Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.需求曲线的移动需求曲线的移动需求需求的变化的变化u需求曲线的移动，向左或者向右。需求曲线的移动，向左或者向右。u是由价格以外的因素变化引起的。是由价格以外

22、的因素变化引起的。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Shifts in the Demand Curve0D1Price of Ice-Cream ConeQuantity of Ice-Cream ConesD3D2Increase in demandDecrease in demandHarcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.需求曲线的移动需求曲线的移动0D1冰激凌蛋卷冰激凌蛋卷的价格

23、的价格冰激凌蛋卷冰激凌蛋卷的数量的数量D3D2需求增加需求增加需求减少需求减少Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Consumer Income 消费者收入消费者收入uAs income increases the demand for a normal good will increase. 收入增加，收入增加，正常商品正常商品的需求增加的需求增加uAs income increases the demand for an inferior good will decrease. 收入增

24、加，收入增加，劣等品劣等品的需求减少的需求减少Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Consumer IncomeNormal Good$3.002.502.001.501.000.502134 56789 101211Price of Ice-Cream ConeQuantity of Ice-Cream Cones0Increasein demandAn increase in income.D1D2Harcourt, Inc. items and derived items copyr

25、ight 2001 by Harcourt, Inc.消费者收入消费者收入 正常商品正常商品$3.002.502.001.501.000.502134 56789 101211冰激凌蛋卷冰激凌蛋卷的价格的价格冰激凌蛋卷冰激凌蛋卷的数量的数量0需求增加需求增加收入增加收入增加.D1D2Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Consumer IncomeInferior Good$3.002.502.001.501.000.502134 56789 101211Price of Ice-Crea

26、m ConeQuantity of Ice-Cream Cones0Decreasein demandAn increase in income.D1D2Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.消费者收入消费者收入 劣等品劣等品$3.002.502.001.501.000.502134 56789 101211冰激凌蛋卷冰激凌蛋卷的价格的价格冰激凌蛋卷冰激凌蛋卷的数量的数量0需求减少需求减少收入增加收入增加.D1D2Harcourt, Inc. items and derived items

27、copyright 2001 by Harcourt, Inc.Prices of Related GoodsSubstitutes & ComplementsuWhen a fall in the price of one good reduces the demand for another good, the two goods are called substitutes.uWhen a fall in the price of one good increases the demand for another good, the two goods are called co

28、mplements.Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.相关物品的价格相关物品的价格替代品和互补品替代品和互补品u当一种物品价格下降减少了另一种物品当一种物品价格下降减少了另一种物品需求时，这两种物品被称为需求时，这两种物品被称为替代品。替代品。u当一种物品价格下降增加了另一种物品当一种物品价格下降增加了另一种物品需求时，这两种物品被称为需求时，这两种物品被称为互补品。互补品。Table 1 Variables That Influence BuyersCopyright2004 Sout

29、h-WesternHarcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.表表1. 影响买者的变量影响买者的变量 变量变量这些变量的变动将这些变量的变动将 . . . 价格价格表现为沿着需求曲线的变动表现为沿着需求曲线的变动 收入收入移动需求曲线移动需求曲线 相关物品价格相关物品价格移动需求曲线移动需求曲线 嗜好嗜好移动需求曲线移动需求曲线预期预期移动需求曲线移动需求曲线 买者数量买者数量移动需求曲线移动需求曲线Harcourt, Inc. items and derived items copyright

30、2001 by Harcourt, Inc.Supply 供给供给Quantity supplied is the amount of a good that sellers are willing and able to sell. 供給量供給量是指卖者愿意而且能够出售的一种是指卖者愿意而且能够出售的一种物品或劳务的数量。物品或劳务的数量。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Law of Supply 供给规律供给规律The law of supply states that there

31、 is a direct (positive) relationship between price and quantity supplied.供给规律供给规律认为，价格与供給量之间的认为，价格与供給量之间的关系是正关系。关系是正关系。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Supply Schedule 供给表供给表The supply schedule is a table that shows the relationship between the price of the good

32、 and the quantity supplied.供给表供给表是表示一种物品价格与供給量之是表示一种物品价格与供給量之间关系的表格。间关系的表格。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Bens Supply Schedule 供给表供给表Price 价格 Quantity 数量 $0.00 0 0.50 0 1.00 1 1.50 2 2.00 3 2.50 4 3.00 5 Harcourt, Inc. items and derived items copyright 2001 b

33、y Harcourt, Inc.Supply Curve 供给曲线供给曲线The supply curve is the upward-sloping line relating price to quantity supplied. 供给曲线供给曲线把价格与供給量联系在把价格与供給量联系在一起的向右上方倾斜的曲线。一起的向右上方倾斜的曲线。Figure 5 Bens Supply Schedule and Supply Curverice ofIce-CreamCone02.502.001.501.0012345678910 11Quantity ofIce-Cream Cones$3.00

34、120.501. Anincrease in price .2. . increases quantity of cones supplied.图图5. Ben供给表与供给曲线供给表与供给曲线冰激凌蛋卷冰激凌蛋卷需求量需求量02.502.001.501.0012345678910 11冰激凌蛋卷的供給量冰激凌蛋卷的供給量$3.00120.501.价格 上升 2. . 供給量增加。价格 数量 $0.00 0 0.50 0 1.00 1 1.50 2 2.00 3 2.50 4 3.00 5 Harcourt, Inc. items and derived items copyright 2001

35、 by Harcourt, Inc.Market Supply versus Individual SupplyuMarket supply refers to the sum of all individual supplies for all sellers of a particular good or service.uGraphically, individual supply curves are summed horizontally to obtain the market supply curve.Harcourt, Inc. items and derived items

36、copyright 2001 by Harcourt, Inc.市场供给市场供给u市场供给市场供给 是指某种物品或劳务的所是指某种物品或劳务的所有卖者个人供给的总和。有卖者个人供给的总和。u从图形上看从图形上看, 把个人供给曲线把个人供给曲线水平水平相加，就得出了市场供给曲线。相加，就得出了市场供给曲线。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Shifts in the Supply CurveuInput pricesuTechnologyuExpectations uNumber of p

37、roducersHarcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.供给曲线的移动供给曲线的移动u投入要素价格投入要素价格u技术技术u预期预期 u生产者数量生产者数量Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Change in Quantity Supplied versus Change in SupplyChange in Quantity SupplieduMovement along the sup

38、ply curve.uCaused by a change in the market price of the product.Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.供給量的变化与供给的变化供給量的变化与供给的变化供給量的变化供給量的变化u沿着供给曲线移动。沿着供给曲线移动。u是由于产品的市场价格变动引起是由于产品的市场价格变动引起的。的。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Chang

39、e in Quantity Supplied1 5Price of Ice-Cream ConeQuantity of Ice-Cream Cones0S 1.00AC$3.00A rise in the price of ice cream cones results in a movement along the supply curve.Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.供給量的变化供給量的变化1 5冰激凌蛋卷冰激凌蛋卷的价格的价格冰激凌蛋卷冰激凌蛋卷的数量的数量0S 1.00AC

40、$3.00冰激凌蛋卷的冰激凌蛋卷的市场价格上升市场价格上升导致供給量沿导致供給量沿着供给曲线的着供给曲线的移动移动。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Shifts in the Supply CurveChange in SupplyuA shift in the supply curve, either to the left or right. uCaused by a change in a determinant other than price.Harcourt, Inc. i

41、tems and derived items copyright 2001 by Harcourt, Inc.供給曲线的移动供給曲线的移动供给的变化供给的变化u供给曲线的移动，向左或者向右。供给曲线的移动，向左或者向右。 u是由于价格以外的因素变化造成的。是由于价格以外的因素变化造成的。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Shifts in the Supply CurvePrice of Ice-Cream ConeQuantity of Ice-Cream Cones0S1S2S3In

42、crease in SupplyDecrease in SupplyHarcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.供给曲线的移动供给曲线的移动冰激凌蛋卷冰激凌蛋卷的价格的价格冰激凌蛋卷冰激凌蛋卷的数量的数量0S1S2S3供给增加供给增加供给减少供给减少Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Table 2 Variables That Influence Sellers Variables A Ch

43、ange in This Variable . . . Price Represents a movement along the supply curve Input prices Shifts the supply curve Technology Shifts the supply curve Expectations Shifts the supply curve Number of sellers Shifts the supply curve Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc

44、.供給量的变化与供给的变化供給量的变化与供给的变化 影影响响供供給給量量的的变变量量 这这种种变变量量的的变变动动将将 . . . 价格 表现为沿着供给曲线的变动 投入要素价格 供给曲线移动 技术 供给曲线移动 预期 供给曲线移动 卖者数量 供给曲线移动 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.SUPPLY AND DEMAND TOGETHER供给与需求的结合供给与需求的结合nEquilibrium refers to a situation in which the price has r

45、eached the level where quantity supplied equals quantity demanded. 市场均衡市场均衡 价格价格水平达到供給量与需求量水平达到供給量与需求量相等的状态。相等的状态。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Supply and Demand TogetherEquilibrium PriceuThe price that balances supply and demand. uOn a graph, it is the price

46、 at which the supply and demand curves intersect.Equilibrium QuantityuThe quantity that balances supply and demand. uOn a graph it is the quantity at which the supply and demand curves intersect. Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.供给与需求的结合供给与需求的结合均衡价格均衡价格u使供给与需求平衡

47、的价格。使供给与需求平衡的价格。u从图形上看，就是供给曲线与需求曲从图形上看，就是供给曲线与需求曲线相交时的价格。线相交时的价格。均衡数量均衡数量u当价格调整到使供给与需求平衡时的当价格调整到使供给与需求平衡时的供給量与需求量。供給量与需求量。u从图形上看，就是供给曲线与需求曲从图形上看，就是供给曲线与需求曲线相交时的数量。线相交时的数量。 Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Supply and Demand TogetherPriceQuantity$0.0000.5001.0011.

48、5042.0072.50103.0013PriceQuantity$0.00190.50161.00131.50102.0072.5043.001Demand ScheduleSupply ScheduleAt $2.00, the quantity demanded is equal to the quantity supplied!Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.供给与需求的结合供给与需求的结合价格 数量 $0.00 0 0.50 0 1.00 1 1.50 4 2.00 7 2.

49、50 10 3.00 13 价格 数量 $0.00 19 0.50 16 1.00 13 1.50 10 2.00 7 2.50 4 3.00 1 需求表需求表供给表供给表在在 $2.00时时, 需求量等于供給量需求量等于供給量!Figure 8 The Equilibrium of Supply and DemandCopyright2003 Southwestern/Thomson LearningPrice ofIce-CreamCone0123456789101112Quantity of Ice-Cream Cones13EquilibriumquantityEquilibrium

50、priceEquilibriumSupplyDemand$2.00表表8. 供给与需求的均衡供给与需求的均衡冰激凌蛋卷冰激凌蛋卷需求量需求量0123456789101112冰激凌蛋卷的数量冰激凌蛋卷的数量13均衡数量均衡价格均衡供给需求$2.00Figure 9 Markets Not in EquilibriumPrice ofIce-CreamCone0SupplyDemand(a) Excess SupplyQuantitydemandedQuantitysuppliedSurplusQuantity ofIce-CreamCones4$2.50102.007图图9. 非均衡状态的市场非

51、均衡状态的市场冰激凌蛋卷冰激凌蛋卷需求量需求量0供给需求(a) 超额供给超额供给 需求量 供给量 过剩冰激凌蛋卷的数量冰激凌蛋卷的数量4$2.50102.007Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.EquilibriumnSurplusWhen price equilibrium price, then quantity supplied quantity demanded. There is excess supply or a surplus. Suppliers will lower

52、the price to increase sales, thereby moving toward equilibrium.Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.均衡均衡n过剩过剩当价格高于均衡价格时，供給量大于当价格高于均衡价格时，供給量大于需求量。需求量。 存在存在超额供给超额供给或或过剩。过剩。 供给者通过降低价格来增加销售，这使价供给者通过降低价格来增加销售，这使价格向其均衡水平变动。格向其均衡水平变动。Harcourt, Inc. items and derived items

53、copyright 2001 by Harcourt, Inc.EquilibriumnShortageWhen price the quantity supplied. There is excess demand or a shortage. Suppliers will raise the price due to too many buyers chasing too few goods, thereby moving toward equilibrium.Harcourt, Inc. items and derived items copyright 2001 by Harcourt

54、, Inc.均衡均衡n短缺短缺当价格低于市场均衡价格时，需求量超当价格低于市场均衡价格时，需求量超过了供給量。过了供給量。 存在着存在着超额需求超额需求或或短缺。短缺。 由于太多卖者要购买太少的物品，供给者由于太多卖者要购买太少的物品，供给者将提高价格。因此价格将趋向于市场均衡将提高价格。因此价格将趋向于市场均衡价格。价格。Figure 9 Markets Not in EquilibriumPrice ofIce-CreamCone0Quantity ofIce-CreamConesSupplyDemand(b) Excess DemandQuantitysuppliedQuantityde

55、manded1.5010$2.0074Shortage图图9. 非均衡状态的市场非均衡状态的市场冰激凌蛋卷冰激凌蛋卷需求量需求量0冰激凌蛋卷的数量冰激凌蛋卷的数量供给供给(b) 超额需求超额需求 供給量 需求量1.5010$2.0074 短缺Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Equilibrium 均衡均衡nLaw of supply and demand 需求需求规律规律The claim that the price of any good adjusts to bring the

56、quantity supplied and the quantity demanded for that good into balance.认为任何一种物品价格的调整都会使该物认为任何一种物品价格的调整都会使该物品供求平衡的观点。品供求平衡的观点。Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Three Steps To Analyzing Changes in EquilibriumuDecide whether the event shifts the supply or demand cur

57、ve (or both).uDecide whether the curve(s) shift(s) to the left or to the right.uUse the supply-and-demand diagram to see how the shift affects equilibrium price and quantity.Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.分析均衡的三个步骤分析均衡的三个步骤u确定该事件是使供给曲线移动，还是确定该事件是使供给曲线移动，还是使需求曲

58、线移动，或者使两种曲线都使需求曲线移动，或者使两种曲线都移动。移动。u确定曲线是向右移动，还是向左移动确定曲线是向右移动，还是向左移动。u用供求图来考察这种移动如何影响均用供求图来考察这种移动如何影响均衡价格和数量。衡价格和数量。How an Increase in Demand Affects the EquilibriumPrice ofIce-CreamCone2.0007Quantity ofIce-Cream ConesSupplyInitialequilibriumD11. Hot weather increasesthe demand for ice cream.D22. .re

59、sultingin a higherprice.$2.50103. .and a higherquantity sold.New equilibrium需求增加如何影响均衡需求增加如何影响均衡冰激凌蛋卷冰激凌蛋卷的价格的价格2.0007冰激凌蛋卷的数量冰激凌蛋卷的数量供给供给原来的原来的均衡均衡D11. 天气热使冰激凌需求增加天气热使冰激凌需求增加.D22. 引起价格引起价格上升上升.$2.50103. 及销售量更多。及销售量更多。新均衡新均衡Harcourt, Inc. items and derived items copyright 2001 by Harcourt, Inc.Three

60、 Steps to Analyzing Changes in Equilibrium nShifts in Curves versus Movements along CurvesA shift in the supply curve is called a change in supply.A movement along a fixed supply curve is called a change in quantity supplied.A shift in the demand curve is called a change in demand.A movement along a fix