彈性及其應(yīng)用經(jīng)濟學(xué)原理中英文雙語課件

1、Elasticity and Its Application彈性及其應(yīng)用Chapter 5Elasticity . . . 彈性 is a measure of how much buyers and sellers respond to changes in market conditions. 是衡量買者和賣者對市場條件變動的反應(yīng)大小的指標。 allows us to analyze supply and demand with greater precision.使我們可以更精確地分析供給與需求Price Elasticity of DemandPrice elasticity of d

2、emand is the percentage change in quantity demanded given a percent change in the price. It is a measure of how much the quantity demanded of a good responds to a change in the price of that good.需求的價格彈性需求的價格彈性價格變化1%引起的需求量的變化百分比值。 它是一種物品的需求量對其價格變動的反應(yīng)程度的衡量。Determinants of Price Elasticity of Demand需求

3、價格彈性的決定因素Necessities versus Luxuries 必需品與奢侈品Availability of Close Substitutes 相近替代品的可獲得性Definition of the Market 市場的定義Time Horizon 時間的長短Determinants of Price Elasticity of DemandDemand tends to be more elastic :if the good is a luxury.the longer the time period.the larger the number of close substit

4、utes.the more narrowly defined the market.價格需求彈性的決定因素需求傾向于富有彈性：如果物品是奢侈品時期更長相近替代品的數(shù)量更多市場定義的范圍更窄Computing the Price Elasticity of DemandThe price elasticity of demand is computed as the percentage change in the quantity demanded divided by the percentage change in price.計算需求價格彈性用需求量變動的百分比除以價格變動的百分比來計算

5、需求價格彈性。Computing the Price Elasticity of DemandExample: If the price of an ice cream cone increases from $2.00 to $2.20 and the amount you buy falls from 10 to 8 cones then your elasticity of demand would be calculated as:計算需求價格彈性例子: 如果冰激凌蛋卷的價格從2美元上升到2.2美元，你的購買量從10個下降到8個，你的需求價格彈性計算如下：The Midpoint Me

6、thod: A Better Way to Calculate Percentage Changes and ElasticitiesThe midpoint formula is preferable when calculating the price elasticity of demand because it gives the same answer regardless of the direction of the change.中點法:一種計算百分比變化和彈性的更好方法中點法 是計算需求價格彈性的更好方法，因為無論變動的方向如何，中點法給出了同一個答案。The Midpoin

7、t Method: A Better Way to Calculate Percentage Changes and ElasticitiesExample: If the price of an ice cream cone increases from $2.00 to $2.20 and the amount you buy falls from 10 to 8 cones the your elasticity of demand, using the midpoint formula, would be calculated as:中點法:一種計算百分比變化和彈性的更好方法例子:如果

8、冰激凌蛋卷的價格從2美元上升到2.2美元，你的購買量從10個下降到8個，利用中點法你的需求價格彈性計算如下：The Variety of Demand CurvesInelastic DemandQuantity demanded does not respond strongly to price changes.Price elasticity of demand is less than one.Elastic DemandQuantity demanded responds strongly to changes in price.Price elasticity of demand

9、is greater than one.多種需求曲線缺乏彈性的需求需求量不隨著價格變化而強烈變化。需求價格彈性小于1。富有彈性的需求需求量隨著價格變化而強烈變化。需求價格彈性大于1。Computing the Price Elasticity of Demand計算需求的價格彈性Demand is price elastic需求富有彈性$54Demand需求Quantity數(shù)量1000Price價格50The Variety of Demand CurvesPerfectly InelasticQuantity demanded does not respond to price change

10、s.Perfectly ElasticQuantity demanded changes infinitely with any change in price.Unit ElasticQuantity demanded changes by the same percentage as the price.多種需求曲線完全無彈性 需求量不隨價格變化而變化。完全彈性 價格極小變化引起需求量極大變動。單位彈性 需求量與價格同比例變動。A Variety of Demand Curves多種需求彈性曲線Because the price elasticity of demand measures

11、how much quantity demanded responds to the price, it is closely related to the slope of the demand curve.由于需求的價格彈性衡量需求量對價格變化的反應(yīng)程度，所以它與需求曲線的斜率密切相關(guān)。Perfectly Inelastic Demand Elasticity equals 0完全無彈性的需求彈性等于0Quantity 數(shù)量Price價格4$5Demand 需求1002. .leaves the quantity demanded unchanged.2.需求量不變。1. Anincrea

12、sein price.1.價格上升Inelastic Demand Elasticity is less than 1缺乏彈性的需求彈性小于1Quantity 數(shù)量Price價格4$51. A 22%increasein price.1.價格上升22Demand 需求100902. .leads to a 11% decrease in quantity.2.使需求量減少11%。Unit Elastic Demand Elasticity equals 1單位需求彈性彈性等于1Quantity 數(shù)量Price價格4$51. A 22%increasein price.1.價格上升22Deman

13、d 需求100802. .leads to a 22% decrease in quantity.2.使需求量減少22。Elastic Demand Elasticity is greater than 1富有彈性的需求彈性大于1Quantity 數(shù)量Price價格4$51. A 22%increasein price.1.價格上升22Demand需求100502. .leads to a 67% decrease in quantity.2.使需求量減少67。Perfectly Elastic Demand- Elasticity equals infinityQuantityPriceDe

14、mand$41. At any priceabove $4, quantitydemanded is zero.2. At exactly $4,consumers willbuy any quantity.3. At a price below $4,quantity demanded is infinite.完全富有彈性彈性等于無窮大數(shù)量價格需求$4在任何高于4美元價格時，需求量為02. 在價格正好為4美元時，消費者將購買任何一種數(shù)量。3. 價格低于4美元時，需求量是無限的。Total Revenue and the Price Elasticity of Demand 總收益與需求價格彈

15、性Total revenue is the amount paid by buyers and received by sellers of a good. 總收益是一種物品買者的支付量和賣者得到的量。Computed as the price of the good times the quantity sold.用該物品的價格乘以銷售量來計算。TR = P x Q$4Demand 需求Quantity數(shù)量P0Price價格P x Q = $400 (total revenue 總收益)100QTotal Revenue and the Price Elasticity of Demand

16、總收益與需求價格彈性Elasticity and Total Revenue along a Linear Demand Curve 沿著線性需求曲線的彈性與總收益With an inelastic demand curve, an increase in price leads to a decrease in quantity that is proportionately smaller. Thus, total revenue increases. 如果需求是缺乏彈性的，價格上升導(dǎo)致需求量減少的比例小于價格上升的比例，所以總收益是增加的。Figure 3 How Total Reven

17、ue Changes When Price Changes: Inelastic Demand$3Quantity0Price80Revenue = $240 Demand$1DemandQuantity0Revenue = $100100 PriceAn increase in price from $1 to $3.leads to an increase in total revenue from$100 to $240圖3.總收益如何隨著價格變化而變化： 缺乏彈性的需求$3數(shù)量0價格80收益=240美元 需求$1需求數(shù)量0收益 = 100美元100 價格價格從1美元上升到3美元.導(dǎo)致總

18、收益從100美元增加到240美元Elasticity and Total Revenue along a Linear Demand Curve 沿著線性需求曲線的彈性與總收益With an elastic demand curve, an increase in the price leads to a decrease in quantity demanded that is proportionately larger. Thus, total revenue decreases.如果需求富有彈性，價格上升導(dǎo)致的需求量減少的比例大于價格上升的比例，因此總收益是減少的。Figure 4 H

19、ow Total Revenue Changes When Price Changes: Elastic DemandDemandQuantity0Price$450DemandQuantity0PriceRevenue = $100 $520Revenue = $200 An increase in price from $4 to $5.leads to a decrease in total revenue from$200 to $100圖4.總收益如何隨著價格變化而變化： 富有彈性的需求需求數(shù)量0價格$450數(shù)量數(shù)量0價格收益 = 100美元 $520收益 =200美元 價格從4美元

20、上升到5美元導(dǎo)致總收益從200美元減少到100美元the Elasticity of a Linear Demand Curve線性需求曲線的彈性Income Elasticity of DemandIncome elasticity of demand measures how much the quantity demanded of a good responds to a change in consumers income. It is computed as the percentage change in the quantity demanded divided by the

21、percentage change in income.需求的收入彈性需求的收入彈性 衡量消費者收入變動時需求量如何變動。 它是需求量變動的百分比除以收入變動的百分比。 Computing Income Elasticity計算收入彈性Income Elasticityof Demand需求的收入彈性Percentage Change in Quantity DemandedPercentage Change in Income收入變動百分比=需求量變動百分比Income Elasticity- Types of Goods收入彈性：不同類型的物品Normal Goods 正常物品Inferi

22、or Goods 劣等品Higher income raises the quantity demanded for normal goodsbut lowers the quantity demanded for inferior goods. 正常物品：收入提高增加需求量；劣等品：收入增加減少需求量。Income Elasticity - Types of Goods -Goods consumers regard as necessities tend to be income inelasticExamples include food, fuel, clothing, utiliti

23、es, and medical services.Goods consumers regard as luxuries tend to be income elastic.Examples include sports cars, furs, and expensive foods.收入彈性：不同類型的物品消費者消費的必需品往往收入彈性小 例如：食物、燃油、衣服、醫(yī)療服務(wù)。消費者消費的奢侈品往往收入彈性大例如：運動跑車、皮衣和昂貴物品。需求的交叉價格彈性需求的交叉價格彈性物品1需求量變動百分比物品2價格變動百分比=替代品： E0互補品： E0無關(guān)物品：E0Price Elasticity of

24、 SupplyPrice elasticity of supply is the percentage change in quantity supplied resulting from a percent change in price.It is a measure of how much the quantity supplied of a good responds to a change in the price of that good.供給的價格彈性供給價格彈性價格變動1引起的供給量的變動百分比值。它是一種物品的供給量對其價格變動的反應(yīng)程度的衡量。Perfectly Inela

25、stic Supply Elasticity equals 0完全無彈性的供給：彈性等于0Quantity 數(shù)量Price價格4$5Supply 供給1002. .leaves the quantity supplied unchanged.2. 供給量不變。1. Anincreasein price.1.價格上升Inelastic Supply Elasticity is less than 1缺乏彈性的供給：彈性小于1Quantity 數(shù)量Price價格4$51. A 22%increasein price.1.價格上升22110100Supply 供給2. .leads to a 10%

26、 increase in quantity.2. 引起供給量增加10。Unit Elastic SupplyElasticity equals 1單位彈性供給：彈性等于1Quantity 數(shù)量Price價格4$51. A 22%increasein price.1.價格上升22125100Supply 供給2. .leads to a 22% increase in quantity.2. 引起供給量增加22。Elastic Supply Elasticity is greater than 1富有彈性的供給：彈性大于1Quantity 數(shù)量Price價格4$51. A 22%increase

27、in price.1.價格上升22200100Supply 供給2. .leads to a 67% increase in quantity.2. 引起供給量增加67。Perfectly Elastic Supply Elasticity equals infinity完全有彈性的供給：彈性等于無窮大Quantity 數(shù)量Price價格Supply 供給$41. At any price above $4, quantitysupplied is infinite.1.在任何高于4美元的價格時，供給量無限。2. At exactly $4, producers willsupply any

28、quantity.2.在正好為4美元時，生產(chǎn)者供給任何一種數(shù)量。3. At a price below $4, quantity supplied is zero.3.在價格低于4美元時，供給量為0。Determinants of Elasticity of Supply Ability of sellers to change the amount of the good they produce.Beach-front land is inelastic.Books, cars, or manufactured goods are elastic. Time period. Supply

29、is more elastic in the long run.供給彈性的決定因素 賣者改變它們生產(chǎn)物品產(chǎn)量的能力海灘前的土地供給是缺乏彈性的。書、汽車或生產(chǎn)的物品供給是富有彈性的。 時間長短 供給在長期內(nèi)更富有彈性。Computing the Price Elasticity of SupplyThe price elasticity of supply is computed as the percentage change in the quantity supplied divided by the percentage change in price.計算供給價格彈性供給價格彈性等于

30、供給量變動百分比除以價格變動百分比。THREE APPLICATIONS OF SUPPLY, DEMAND, AND ELASTICITY 供給、需求與彈性的三個應(yīng)用Can good news for farming be bad news for farmers?農(nóng)業(yè)的好消息會是農(nóng)民的壞消息嗎？What happens to wheat farmers and the market for wheat when university agronomists discover a new wheat hybrid that is more productive than existing v

31、arieties?當大學(xué)的農(nóng)業(yè)科學(xué)家培育出能比現(xiàn)有品種更高產(chǎn)的小麥新雜交品種時，種小麥的農(nóng)民會怎么辦？小麥市場又會發(fā)生什么變動呢？THREE APPLICATIONS OF SUPPLY, DEMAND, AND ELASTICITY 供給、需求與彈性的三個應(yīng)用Examine whether the supply or demand curve shifts. 考察是供給曲線還是需求曲線移動。Determine the direction of the shift of the curve. 考慮曲線向哪個方向移動。Use the supply-and-demand diagram to se

32、e how the market equilibrium changes. 用供求圖說明市場均衡如何變動。3. .and a proportionately smallerincrease in quantity sold. As a result,revenue falls from $300 to $220.An Increase in Supply in the Market for Wheat$3Quantity of Wheat1000Price ofWheat1. When demand is inelastic,an increase in supply.DemandS1S221

33、102. .leadsto a large fall in price.3. 以及銷售量的小幅度增加。結(jié)果收益從300美元減少為220美元。小麥市場上供給增加$3小麥數(shù)量1000小麥價格當需求缺乏彈性時，供給增加.需求S1S221102. 引起價格的大幅度下降.Compute the Price Elasticity of Supply 計算供給價格彈性Demand is inelastic 需求缺乏彈性56$74123Quantity 數(shù)量12246810140Price價格Elasticity is larger than 1.彈性大于1Elasticity isSmaller than

34、1.彈性小于1Figure 5-5$15123Quantity數(shù)量1002005000Price 價格525Elasticity is small(less than 1).Elasticity is large(greater than 1).4Figure 5-7彈性小（1）P2P1Quantity of Oil0Priceof OilDemandS2S1(a) The Oil Market in the Short RunP2P1Quantity of Oil0Priceof OilDemandS2S1(b) The Oil Market in the Long Run2. .leads

35、to a largeincreasein price.1. In the long run,when supply anddemand are elastic,a shift in supply.2. .leadsto a smallincreasein price.1. In the short run, when supplyand demand are inelastic,a shift in supply.Figure 5-9P2P1石油數(shù)量0石油價格需求S2S1(a) 短期石油市場P2P1石油數(shù)量0石油價格需求S2S1(b) 長期石油市場2. .引起價格大幅度上升在長期中，當供給與需

36、求富有彈性時，供給移動2. .引起價格小幅度上升在短期中，當供給和需求缺乏彈性時，供給移動Figure 5-9P2P1Quantity of Drugs0Q2Q1Price ofDrugsDemandS2S1Q2Q1(a) Drug InterdictionQuantity of Drugs0Price ofDrugsSupplyD2D1(b) Drug Education3. .and reduces the quantity sold.2. .whichraises theprice.2. .whichreducesthe price.P1P21. Drug interdiction re

37、ducesthe supply of drugs.1. Drug education reducesthe demand for drugs.3. .and reduces the quantity sold.Figure 5-10P2P1毒品數(shù)量0Q2Q1毒品價格需求S2S1Q2Q1(a) 禁毒毒品數(shù)量0毒品價格供給D2D1(b) 禁毒教育3. 以及減少了銷售量。2. 提高了價格2. 降低了價格P1P21. 禁毒減少了毒品供給1. 禁毒教育減少了毒品需求3. 以及減少了銷售量 。Figure 5-10SummaryPrice elasticity of demand measures how much the quantity dem