第章彈性及其應(yīng)用

1、第5章 彈性及其應(yīng)用要點(diǎn)：彈性含義需求彈性供給彈性彈性彈性 衡量買者與賣者對(duì)市場(chǎng)條件變動(dòng)反應(yīng)大小的指標(biāo)。需求價(jià)格彈性需求價(jià)格彈性：一種物品需求量對(duì)其價(jià)格變動(dòng)反應(yīng)程度的衡量，用需求量變動(dòng)的百分比除以價(jià)格變動(dòng)的百分比來(lái)計(jì)算。如果一種物品需求量對(duì)價(jià)格變動(dòng)的反應(yīng)大，我們可以說(shuō)這種物品是富有彈性的。如果一種物品需求量對(duì)價(jià)格變動(dòng)的反應(yīng)小，我們可以說(shuō)這種物品是缺乏彈性的。什么因素決定一種物品需求富有彈性還是缺乏彈性？必需品與奢侈品相近替代品的可獲得性市場(chǎng)的定義時(shí)間的長(zhǎng)短計(jì)算需求價(jià)格彈性 需求量變動(dòng)的百分比需求價(jià)格彈性= 價(jià)格變動(dòng)的百分比中點(diǎn)法：計(jì)算百分比變動(dòng)和彈性的一種更好方法需求曲線的變化拇指規(guī)則：通過(guò)某

2、一點(diǎn)的需求曲線越平坦，需求的價(jià)格彈性就越大。通過(guò)某一點(diǎn)的需求曲線越陡峭，需求的價(jià)格彈性就越小。完全無(wú)彈性的需求：彈性等于0(a) Perfectly Inelastic Demand: Elasticity Equals 0$54QuantityDemand10001. Anincreasein price . . .2. . . . leaves the quantity demanded unchanged.Price缺乏彈性的需求：彈性小于1(b) Inelastic Demand: Elasticity Is Less Than 1Quantity0$590Demand1. A 22%

3、increasein price . . .Price2. . . . leads to an 11% decrease in quantity demanded.4100單位彈性需求：彈性等于12. . . . leads to a 22% decrease in quantity demanded.(c) Unit Elastic Demand: Elasticity Equals 1Quantity41000Price$5801. A 22%increasein price . . .Demand富有彈性的需求：彈性大于1(d) Elastic Demand: Elasticity Is

4、 Greater Than 1DemandQuantity41000Price$5501. A 22%increasein price . . .2. . . . leads to a 67% decrease in quantity demanded.完全富有彈性的需求：彈性等于無(wú)窮大(e) Perfectly Elastic Demand: Elasticity Equals InfinityQuantity0Price$4Demand2. At exactly $4,consumers willbuy any quantity.1. At any priceabove $4, quant

5、itydemanded is zero.3. At a price below $4,quantity demanded is infinite.總收益與需求的價(jià)格彈性一種物品的價(jià)格乘以該物品的銷售量總收益DemandQuantityQP0Price P Q = $400(revenue)$4100When the price is $4, consumers will demand 100 units, and spend $400 on this good.當(dāng)價(jià)格變動(dòng)時(shí)總收益如何變動(dòng)：缺乏彈性的需求DemandQuantity0PriceRevenue = $100 Quantity0Pr

6、iceRevenue = $240 Demand$1100$380An Increase in price from $1 to $3 leads to an Increase in total revenue from $100 to $240當(dāng)價(jià)格變動(dòng)時(shí)總收益如何變動(dòng)：富有彈性的需求DemandQuantity0PriceRevenue = $200 $450DemandQuantity0PriceRevenue = $100 $520An Increase in price from $4 to $5 leads to an decrease in total revenue from

7、$200 to $100Note that with each price increase, the Law of Demand still holds an increase in price leads to a decrease in the quantity demanded. It is the change in TR that varies!當(dāng)需求曲線缺乏彈性時(shí)（e1），價(jià)格上升使總收益減少，價(jià)格下降使總收益增加。當(dāng)需求單位彈性時(shí)（e=1），價(jià)格的變動(dòng)不影響總收益。02641081214214356$7Demand is elastic; demand is responsiv

8、e to changes in price.Demand is inelastic; demand is not very responsive to changes in price.When price increases from $4 to $5, TR declines from $24 to $20. When price increases from $2 to $3, TR increases from $20 to $24. Elasticity is 1 in this range.Elasticity is 1 in this range.PriceQuantity沿著一

9、條線性曲線的彈性和總收益其他需求彈性需求收入彈性需求交叉價(jià)格彈性供給彈性供給價(jià)格彈性：一種物品供給量對(duì)其價(jià)格變動(dòng)反應(yīng)程度的衡量。在大多數(shù)市場(chǎng)上，供給價(jià)格彈性決定因素是考慮時(shí)間的長(zhǎng)短，供給在長(zhǎng)期中的彈性通常大于短期。 供給量變動(dòng)百分比供給價(jià)格彈性= 價(jià)格變動(dòng)百分比完全無(wú)彈性的供給：彈性等于0(a) Perfectly Inelastic Supply: Elasticity Equals 0$54SupplyQuantity10001. Anincreasein price . . .2. . . . leaves the quantity supplied unchanged.Price缺乏彈

10、性的供給，彈性1(b) Inelastic Supply: Elasticity Is Less Than 1110$51004Quantity01. A 22%increasein price . . .Price2. . . . leads to a 10% increase in quantity supplied.Supply單位彈性供給，彈性等于1(c) Unit Elastic Supply: Elasticity Equals 1125$51004Quantity0Price2. . . . leads to a 22% increase in quantity supplied

11、.1. A 22%increasein price . . .Supply(If SUPPLY is unit elastic and linear, it will begin at the origin.)富有彈性供給，彈性大于1(d) Elastic Supply: Elasticity Is Greater Than 1Quantity0Price1. A 22%increasein price . . .2. . . . leads to a 67% increase in quantity supplied.4100$5200Supply完全有彈性的供給，彈性等于無(wú)限大(e) Perfectly Elastic Supply: Elasticity Equals Infinity