经济学原理Chap05曼昆.ppt

Elasticity and Its ApplicationChapter 5Copyright © 2001 by Harcourt, Inc.All rights reserved.   Requests for permission to make copies of any part of thework should be mailed to:Permissions Department, Harcourt College Publishers,6277 Sea Harbor Drive, Orlando, Florida 32887-6777.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elasticity . . .u … is a measure of how much buyers and sellers respond to changes in market conditions u … allows us to analyze supply and demand with greater precision.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Price Elasticity of DemanduPrice elasticity of demand is the percentage change in quantity demanded given a percent change in the price. uIt is a measure of how much the quantity demanded of a good responds to a change in the price of that good.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Determinants of Price Elasticity of DemanduNecessities versus LuxuriesuAvailability of Close SubstitutesuDefinition of the MarketuTime HorizonHarcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Determinants of Price Elasticity of DemandDemand tends to be more elastic :uif the good is a luxury.uthe longer the time period.uthe larger the number of close substitutes.uthe more narrowly defined the market.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.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.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.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:Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Computing the Price Elasticity of Demand Using the Midpoint FormulaThe midpoint formula is preferable when calculating the price elasticity of demand because it gives the same answer regardless of the direction of the change.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.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 the your elasticity of demand, using the midpoint formula, would be calculated as:Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Ranges of ElasticityInelastic DemanduQuantity demanded does not respond strongly to price changes.uPrice elasticity of demand is less than one.Elastic DemanduQuantity demanded responds strongly to changes in price.uPrice elasticity of demand is greater than one.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Computing the Price Elasticity of DemandDemand is price elastic$54DemandQuantity1000Price50Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Ranges of ElasticityuPerfectly InelasticQuantity demanded does not respond to price changes.uPerfectly ElasticQuantity demanded changes infinitely with any change in price.uUnit ElasticQuantity demanded changes by the same percentage as the price.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.A Variety of Demand CurvesBecause 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.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Perfectly Inelastic Demand- Elasticity equals 0QuantityPrice4$5Demand1002. ...leaves the quantity demanded unchanged.1. Anincreasein price...Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Inelastic Demand- Elasticity is less than 1QuantityPrice4$51. A 22%increasein price...Demand100902. ...leads to a 11% decrease in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Unit Elastic Demand- Elasticity equals 1QuantityPrice4$51. A 22%increasein price...Demand100802. ...leads to a 22% decrease in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elastic Demand- Elasticity is greater than 1QuantityPrice4$51. A 22%increasein price...Demand100502. ...leads to a 67% decrease in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Perfectly Elastic Demand- Elasticity equals infinityQuantityPriceDemand$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.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elasticity and Total RevenueuTotal revenue is the amount paid by buyers and received by sellers of a good.uComputed as the price of the good times the quantity sold.TR = P x QHarcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.$4DemandQuantityP0PriceP x Q = $400 (total revenue)100QElasticity and Total RevenueHarcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elasticity and Total RevenueWith an inelastic demand curve, an increase in price leads to a decrease in quantity that is proportionately smaller. Thus, total revenue increases. Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elasticity and Total Revenue: 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Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elasticity and Total RevenueWith an elastic demand curve, an increase in the price leads to a decrease in quantity demanded that is proportionately larger. Thus, total revenue decreases.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elasticity and Total Revenue: 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Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Computing the Elasticity of a Linear Demand CurveHarcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Income Elasticity of DemanduIncome elasticity of demand measures how much the quantity demanded of a good responds to a change in consumers’ income. uIt is computed as the percentage change in the quantity demanded divided by the percentage change in income.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc. Computing Income ElasticityIncome Elasticityof DemandPercentage Change in Quantity DemandedPercentage Change in Income=Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Income Elasticity- Types of Goods -uNormal GoodsuInferior GoodsuHigher income raises the quantity demanded for normal goods but lowers the quantity demanded for inferior goods. Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Income Elasticity- Types of Goods -uGoods consumers regard as necessities tend to be income inelasticExamples include food, fuel, clothing, utilities, and medical services.uGoods consumers regard as luxuries tend to be income elastic.Examples include sports cars, furs, and expensive foods.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Price Elasticity of SupplyuPrice elasticity of supply is the percentage change in quantity supplied resulting from a percent change in price.uIt is a measure of how much the quantity supplied of a good responds to a change in the price of that good.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Ranges of ElasticityuPerfectly ElasticES = ¥ ¥uRelatively ElasticES > 1uUnit ElasticES = 1Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Ranges of ElasticityuRelatively InelasticES < 1uPerfectly InelasticES = 0 Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Perfectly Inelastic Supply- Elasticity equals 0QuantityPrice4$5Supply1002. ...leaves the quantity supplied unchanged.1. Anincreasein price...Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Inelastic Supply- Elasticity is less than 1QuantityPrice4$51. A 22%increasein price...110100Supply2. ...leads to a 10% increase in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Unit Elastic Supply- Elasticity equals 1QuantityPrice4$51. A 22%increasein price...125100Supply2. ...leads to a 22% increase in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elastic Supply- Elasticity is greater than 1QuantityPrice4$51. A 22%increasein price...200100Supply2. ...leads to a 67% increase in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Perfectly Elastic Supply- Elasticity equals infinityQuantityPriceSupply$41. At any priceabove $4, quantitysupplied is infinite.2. At exactly $4,producers willsupply any quantity.3. At a price below $4,quantity supplied is zero.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Determinants of Elasticity of SupplyuAbility of sellers to change the amount of the good they produce.uBeach-front land is inelastic.uBooks, cars, or manufactured goods are elastic.uTime period. uSupply is more elastic in the long run.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.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.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Application of ElasticityuCan good news for farming be bad news for farmers?uWhat happens to wheat farmers and the market for wheat when university agronomists discover a new wheat hybrid that is more productive than existing varieties?Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Application of ElasticityuExamine whether the supply or demand curve shifts.uDetermine the direction of the shift of the curve.uUse the supply-and-demand diagram to see how the market equilibrium changes.An Increase in Supply in the Market for Wheat$3Quantity of Wheat1000Price ofWheatDemandS1Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.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...DemandS1S221102. ...leadsto a large fall in price...Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Compute ElasticityHarcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Compute ElasticityDemand is inelasticHarcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.SummaryuPrice elasticity of demand measures how much the quantity demanded responds to changes in the price. uIf a demand curve is elastic, total revenue falls when the price rises. uIf it is inelastic, total revenue rises as the price rises. Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.SummaryuThe price elasticity of supply measures how much the quantity supplied responds to changes in the price. uIn most markets, supply is more elastic in the long run than in the short run. Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Graphical ReviewHarcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Computing the Price Elasticity of DemandDemand is price elastic$54DemandQuantity1000Price50Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Perfectly Inelastic Demand- Elasticity equals 0QuantityPrice4$5Demand1002. ...leaves the quantity demanded unchanged.1. Anincreasein price...Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Inelastic Demand- Elasticity is less than 1QuantityPrice4$51. A 22%increasein price...Demand100902. ...leads to a 11% decrease in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Unit Elastic Demand- Elasticity equals 1QuantityPrice4$51. A 22%increasein price...Demand100802. ...leads to a 22% decrease in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elastic Demand- Elasticity is greater than 1QuantityPrice4$51. A 22%increasein price...Demand100502. ...leads to a 67% decrease in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Perfectly Elastic Demand- Elasticity equals infinityQuantityPriceDemand$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.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.$4DemandQuantityP0PriceP P x x Q Q = = $400$400 (total revenue)(total revenue)100QElasticity and Total RevenueHarcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elasticity and Total Revenue: 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Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elasticity and Total Revenue: 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Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Perfectly Inelastic Supply- Elasticity equals 0QuantityPrice4$5Supply1002. ...leaves the quantity supplied unchanged.1. Anincreasein price...Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Inelastic Supply- Elasticity is less than 1QuantityPrice4$51. A 22%increasein price...110100Supply2. ...leads to a 10% increase in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Unit Elastic Supply- Elasticity equals 1QuantityPrice4$51. A 22%increasein price...125100Supply2. ...leads to a 22% increase in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Elastic Supply- Elasticity is greater than 1QuantityPrice4$51. A 22%increasein price...200100Supply2. ...leads to a 67% increase in quantity.Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.Perfectly Elastic Supply- Elasticity equals infinityQuantityPriceSupply$41. At any priceabove $4, quantitysupplied is infinite.2. At exactly $4,producers willsupply any quantity.3. At a price below $4,quantity supplied is zero.An Increase in Supply in the Market for Wheat$3Quantity of Wheat1000Price ofWheatDemandS1Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.An Increase in Supply in the Market for Wheat3. ...and a proportionately smallerincrease in quantity sold. As a result,revenue falls from $300 to $220.$3Quantity of Wheat1000Price ofWheat1. When demand is inelastic,an increase in supply...DemandS1S221102. ...leadsto a large fall in price...Harcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc.。