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1、,Elasticity and Its Application 弹性及其应用,Chapter 5,2,Elasticity . . . 弹性, is a measure of how much buyers and sellers respond to changes in market conditions. 是衡量买者和卖者对市场条件变动的反应大小的指标。 allows us to analyze supply and demand with greater precision. 使我们可以更精确地分析供给与需求,3,Price Elasticity of Demand,Price ela
2、sticity of demand 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.,4,需求的价格弹性,需求的价格弹性价格变化1%引起的需求量的变化百分比值。 它是一种物品的需求量对其价格变动的反应程度的衡量。,5,Determinants of Price Ela
3、sticity of Demand 需求价格弹性的决定因素,Necessities versus Luxuries 必需品与奢侈品 Availability of Close Substitutes 相近替代品的可获得性 Definition of the Market 市场的定义 Time Horizon 时间的长短,6,Determinants of Price Elasticity of Demand,Demand tends to be more elastic : if the good is a luxury. the longer the time period. the lar
4、ger the number of close substitutes. the more narrowly defined the market.,7,价格需求弹性的决定因素,需求倾向于富有弹性： 如果物品是奢侈品 时期更长 相近替代品的数量更多 市场定义的范围更窄,8,Computing the Price Elasticity of Demand,The price elasticity of demand is computed as the percentage change in the quantity demanded divided by the percentage cha
5、nge in price.,9,计算需求价格弹性,用需求量变动的百分比除以价格变动的百分比来计算需求价格弹性。,10,Computing the Price Elasticity of Demand,Example: 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:,11,计算需求价格弹性,例子: 如果冰激凌蛋卷的
6、价格从2美元上升到2.2美元，你的购买量从10个下降到8个，你的需求价格弹性计算如下：,12,The Midpoint Method: A Better Way to Calculate Percentage Changes and Elasticities,The midpoint formula is preferable when calculating the price elasticity of demand because it gives the same answer regardless of the direction of the change.,13,中点法:一种计算
7、百分比变化 和弹性的更好方法,中点法 是计算需求价格弹性的更好方法，因为无论变动的方向如何，中点法给出了同一个答案。,14,The Midpoint Method: A Better Way to Calculate Percentage Changes and Elasticities,Example: 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, usi
8、ng the midpoint formula, would be calculated as:,15,中点法:一种计算百分比变化和弹性的更好方法,例子:如果冰激凌蛋卷的价格从2美元上升到2.2美元，你的购买量从10个下降到8个，利用中点法你的需求价格弹性计算如下：,16,The Variety of Demand Curves,Inelastic Demand Quantity demanded does not respond strongly to price changes. Price elasticity of demand is less than one. Elastic De
9、mand Quantity demanded responds strongly to changes in price. Price elasticity of demand is greater than one.,17,多种需求曲线,缺乏弹性的需求 需求量不随着价格变化而强烈变化。 需求价格弹性小于1。 富有弹性的需求 需求量随着价格变化而强烈变化。 需求价格弹性大于1。,18,Computing the Price Elasticity of Demand 计算需求的价格弹性,Demand is price elastic 需求富有弹性,$5,4,Demand 需求,Quantity
10、数量,100,0,Price 价格,50,19,The Variety of Demand Curves,Perfectly Inelastic Quantity demanded does not respond to price changes. Perfectly Elastic Quantity demanded changes infinitely with any change in price. Unit Elastic Quantity demanded changes by the same percentage as the price.,20,多种需求曲线,完全无弹性 需
11、求量不随价格变化而变化。 完全弹性 价格极小变化引起需求量极大变动。 单位弹性 需求量与价格同比例变动。,21,A Variety of Demand Curves 多种需求弹性曲线,Because the price elasticity of demand measures how much quantity demanded responds to the price, it is closely related to the slope of the demand curve. 由于需求的价格弹性衡量需求量对价格变化的反应程度，所以它与需求曲线的斜率密切相关。,22,Perfectly
12、 Inelastic Demand Elasticity equals 0 完全无弹性的需求弹性等于0,Quantity 数量,Price 价格,2. .leaves the quantity demanded unchanged. 2.需求量不变。,23,Inelastic Demand Elasticity is less than 1 缺乏弹性的需求弹性小于1,Quantity 数量,Price 价格,24,Unit Elastic Demand Elasticity equals 1 单位需求弹性弹性等于1,Quantity 数量,Price 价格,25,Elastic Demand
13、Elasticity is greater than 1 富有弹性的需求弹性大于1,Quantity 数量,Price 价格,26,Perfectly Elastic Demand - Elasticity equals infinity,Quantity,Price,27,完全富有弹性弹性等于无穷大,数量,价格,28,Total Revenue and the Price Elasticity of Demand 总收益与需求价格弹性,Total revenue is the amount paid by buyers and received by sellers of a good. 总
14、收益是一种物品买者的支付量和卖者得到的量。 Computed as the price of the good times the quantity sold. 用该物品的价格乘以销售量来计算。 TR = P x Q,29,$4,Demand 需求,Quantity 数量,P,0,Price 价格,P x Q = $400,(total revenue 总收益),100,Total Revenue and the Price Elasticity of Demand 总收益与需求价格弹性,30,Elasticity and Total Revenue along a Linear Demand
15、 Curve 沿着线性需求曲线的弹性与总收益,With an inelastic demand curve, an increase in price leads to a decrease in quantity that is proportionately smaller. Thus, total revenue increases. 如果需求是缺乏弹性的，价格上升导致需求量减少的比例小于价格上升的比例，所以总收益是增加的。,31,Figure 3 How Total Revenue Changes When Price Changes: Inelastic Demand,$3,Quan
16、tity,0,Price,80,Revenue = $240,Demand,$1,Demand,Quantity,0,Revenue = $100,100,Price,An increase in price from $1 to $3.,leads to an increase in total revenue from$100 to $240,32,图3.总收益如何随着价格变化而变化： 缺乏弹性的需求,$3,数量,0,价格,80,收益=240美元,需求,$1,需求,数量,0,收益 = 100美元,100,价格,价格从1美元上升到3美元.,导致总收益从100美元增加到240美元,33,Elasticity and Total Revenue along a Linear Demand Curve 沿着线性需求曲线的弹性与总收益,With an elastic demand curve, an increase i
