Elasticity and its Application

C H A P T E R

Elasticity and its Elasticity and its ApplicationApplication

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弹性及其应用弹性及其应用

In this chapter, In this chapter, look for the answers to these look for the answers to these questions:questions:

What is elasticity? What kinds of issues can elasticity help us understand?

What is the price elasticity of demand? How is it related to the demand curve? How is it related to revenue & expenditure?

What is the price elasticity of supply? How is it related to the supply curve?

What are the income and cross-price elasticities of demand?

什么是弹性？弹性能帮助我们理解什么问题？

什么是需求价格弹性？它与需求曲线有什么联系？它与收益与支出又有什么联系？

什么是供给价格弹性？它与供给曲线有什么联系？

什么是需求收入弹性与需求的交叉价格弹性？

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A scenario… 一个故事

You design websites for local businesses. You charge $200 per website, and currently sell 12 websites per month.

Your costs are rising (including the opportunity cost of your time), so you consider raising the price to $250.

The law of demand says that you won’t sell as many websites if you raise your price. How many fewer websites? How much will your revenue fall, or might it increase?

You design websites for local businesses. You charge $200 per website, and currently sell 12 websites per month.

Your costs are rising (including the opportunity cost of your time), so you consider raising the price to $250.

The law of demand says that you won’t sell as many websites if you raise your price. How many fewer websites? How much will your revenue fall, or might it increase?

你的工作是为本地企业制作网站，制作一个网站收费200美元。目前你每个月能卖出 12个网站

你的成本在不断上升（包括你的时间的机会成本），因此你考虑把价格升到250美元

需求定理告诉我们：如果提高价格，你将不能卖出原来这么多的网站。你将少卖出多少网站？你的收益将会减少还是增加？减少或增加多少？

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ELASTICITY AND ITS APPLICATION 4

Elasticity 弹性 Basic idea:

Elasticity measures how much one variable responds to changes in another variable. One type of elasticity

measures how much demand for your websites will fall if you raise your price.

Definition: Elasticity is a numerical measure of the responsiveness of Qd or Qs to one of its determinants.

基本想法：弹性衡量一种变量对另一种变量反应程度的指标一种弹性衡量如果你提高价格，对你网站的需求会下降多少 ?

定义 : 弹性衡量需求量或供给量对其某种决定因素的反应程度的指标


Price Elasticity of Demand需求价格弹性

Price elasticity of demand measures how much Qd responds to a change in P.

需求价格弹性衡量一种物品需求量对其价格变动反应程度的指标

Price elasticity of demand

=Percentage change in Qd

Percentage change in P

Loosely speaking, it measures the price-sensitivity of buyers’ demand.

简单的说，它衡量卖者需求的价格敏感程度


Price Elasticity of Demand

Price elasticity

of demand equals

P

Q

D

Q2

P2

P1

Q1

P rises by 10%

Q falls by 15%

15%

10%= 1.5




Example:


Price Elasticity of Demand

Along a D curve, P and Q move in opposite directions, which would make price elasticity negative.

We will drop the minus sign and report all price elasticities as positive numbers.

需求与价格沿着需求曲线往相反方向变化，这使需求价格弹性为负。我们去掉负号，把所有价格弹性表示为正数

Along a D curve, P and Q move in opposite directions, which would make price elasticity negative.

We will drop the minus sign and report all price elasticities as positive numbers.

需求与价格沿着需求曲线往相反方向变化，这使需求价格弹性为负。我们去掉负号，把所有价格弹性表示为正数

P

Q

D

Q2

P2

P1

Q1





Calculating Percentage Changes

P

Q

D

$250

8

B

$200

12

A

Demand for your websites

Standard method of computing the percentage (%) change:

end value – start value

start valuex 100%

Going from A to B, the % change in P equals

($250–$200)/$200 = 25%



P

Q

D

$250

8

B

$200

12

A


The standard method gives different answers depending on where you start.如果你的初始值不同，标准方法计算出来的结果也就不同

From A to B, P rises 25%, Q falls 33%,elasticity = 33/25 = 1.33

From B to A, P falls 20%, Q rises 50%, elasticity = 50/20 = 2.50



So, we instead use the midpoint method:

end value – start valuemidpoint中点

x 100%

The midpoint is the number halfway between the start & end values, the average of those values.中点是初始值与终值的平均值

It doesn’t matter which value you use as the “start” and which as the “end” – you get the same answer either way!哪一点看作初始值还是终值并不重要 ---你都会得到相同的结果


Calculating Percentage Changes Using the midpoint method, the % change

in P equals

$250 – $200$225

x 100% = 22.2%

The % change in Q equals

12 – 810

x 100% = 40.0%

The price elasticity of demand equals

40/22.2 = 1.8

A C T I V E L E A R N I N G A C T I V E L E A R N I N G 11

Calculate an elasticityCalculate an elasticity

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Use the following information to calculate the price elasticity of demand for hotel rooms:

if P = $70, Qd = 5000

if P = $90, Qd = 3000


AnswersAnswers

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Use midpoint method to calculate % change in Qd

(5000 – 3000)/4000 = 50%

% change in P

($90 – $70)/$80 = 25%

The price elasticity of demand equals

50%25%

= 2.0


What determines price elasticity?To learn the determinants of price

elasticity, we look at a series of examples. Each compares two common goods.

In each example:

Suppose the prices of both goods rise by 20%.

The good for which Qd falls the most (in percent) has the highest price elasticity of demand. Which good is it? Why?

What lesson does the example teach us about the determinants of the price elasticity of demand?

为了找到需求价格弹性的决定因素，我们看下面的这些例子。每个例子都比较了两种物品。

在每个例子中 :

假设两种物品的价格都上升了 20%

需求数量下降最大 (百分比 )的物品有最大的需求价格弹性。它是哪种物品？为什么？

这个例子告诉我们什么是决定需求价格弹性的因素


EXAMPLE 1: Breakfast cereal vs. Sunscreen 谷类早餐vs. 防晒霜

The prices of both of these goods rise by 20%. For which good does Qd drop the most? Why?

Breakfast cereal has close substitutes (e.g., pancakes, Eggo waffles, leftover pizza), so buyers can easily switch if the price rises.

Sunscreen has no close substitutes, so consumers would probably not

buy much less if its price rises. Lesson: Price elasticity is higher

when close substitutes are available.

这两种物品的价格都上升20%。哪种物品的需求数量下降的最多？为什么？谷类早餐有很多相近的替代品（比如，煎饼， Eggo华夫饼，剩余的皮萨等），如果价格上升买者可以很容易购买其他物品

防晒霜没有类似的替代品，如果价格上升，消费者不可能少买太多

总结：有相近替代品的物品的需求往往较富有弹性


EXAMPLE 2:“Blue Jeans” vs. “Clothing” “ 蓝色牛仔裤”与 “衣服” The prices of both goods rise by 20%.

For which good does Qd drop the most? Why? For a narrowly defined good such

as blue jeans, there are many substitutes (khakis, shorts, Speedos).

There are fewer substitutes available for broadly defined goods. (There aren’t too many substitutes for clothing, other than living in a nudist colony.)

Lesson: Price elasticity is higher for narrowly defined goods than broadly defined ones.

如果两种物品的价格都上涨20%，哪种物品的需求量下降的最多？为什么？定义范围狭窄的物品比如蓝色牛仔裤有很多的替代品（卡其，短裤， Speedos等）

定义范围宽泛的物品很少有替代品（衣服没有什么替代品，除非是流行裸体的殖民地）

总结：范围小的市场的需求弹性往往大于范围大的市场的需求弹性


EXAMPLE 3:Insulin vs. Caribbean Cruises 胰岛素与加勒比游轮 The prices of both of these

goods rise by 20%. For which good does Qd drop the most? Why?

To millions of diabetics, insulin is a necessity. A rise in its price would cause little or no decrease in demand.

A cruise is a luxury. If the price rises, some people will forego it.

Lesson: Price elasticity is higher for luxuries than for necessities.

如果两种物品的价格都上涨 20%，哪种物品的需求量下降的最多？为什么？对数以百万计的糖尿病

患者来说，胰岛素是必需品。胰岛素价格的上升基本上不会引起需求的下降

游轮是奢侈品，如果价格上升，有些人会放弃购买

总结：奢侈品的需求弹性要大于必需品的需求弹性


EXAMPLE 4:Gasoline in the Short Run vs. Gasoline in the Long Run 短期的汽油与长期的汽油 The price of gasoline rises 20%.

Does Qd drop more in the short run or the long run? Why?

There’s not much people can do in the short run, other than ride the bus or carpool.

In the long run, people can buy smaller cars or live closer to where they work.

Lesson: Price elasticity is higher in the long run than the short run.

汽油价格上涨 20%，短期还是长期的汽油需求量会下降更多？为什么？短期内，人们除了坐公交或者自己开车之外，并没有什么其他办法

长期中，人们可以购买省油的小排量汽车或搬到上班地方附近居住

总结：相对于短期，物品的需求往往在长期更富有弹性


The Determinants of Price Elasticity: A Summary

The price elasticity of demand depends on:

the extent to which close substitutes are available

whether the good is a necessity or a luxury

how broadly or narrowly the good is defined

the time horizon – elasticity is higher in the long run than the short run

The price elasticity of demand depends on:

the extent to which close substitutes are available

whether the good is a necessity or a luxury

how broadly or narrowly the good is defined

the time horizon – elasticity is higher in the long run than the short run

需求价格弹性取决于：相近替代品的可获得性

物品是必需品还是奢侈品

物品的定义是宽泛还是狭义

时间框架—长期比短期更富有弹性


The Variety of Demand Curves 各种需求曲线

The price elasticity of demand is closely related to the slope of the demand curve.

Rule of thumb: The flatter the curve, the bigger the elasticity. The steeper the curve, the smaller the elasticity.

Five different classifications of D curves.…

需求价格弹性与需求曲线的斜率密切相关

拇指规则：通过某一点的需求曲线越平坦，需求的价格弹性就越大通过某一点的需求曲线越陡峭，需求的价格弹性就越小

需求曲线的五种不同分类 .…


Q1

P1

D

“ Perfectly inelastic demand” (one extreme case) “ 完全无弹性的需求” (一个极端例子 )

P

Q

P2

P falls by 10%

Q changes by 0%

0%

10%= 0

Price elasticity

of demand

=% change in Q

% change in P=

Consumers’ price sensitivity:消费者的价格敏感度

D curve:

Elasticity:

vertical

none

0


D

“ Inelastic demand” “ 缺乏弹性的需求”

P

QQ1

P1

Q2

P2

Q rises less than 10%

< 10%

10%< 1

Price elasticity

of demand

=% change in Q

% change in P=

P falls by 10%

Consumers’ price sensitivity:

D curve:

Elasticity:

relatively steep相对陡峭

relatively low

< 1


D

“ Unit elastic demand” “ 单位弹性需求”

P

QQ1

P1

Q2

P2

Q rises by 10%

10%

10%= 1

Price elasticity

of demand

=% change in Q

% change in P=

P falls by 10%


Elasticity:

intermediate

1

D curve:intermediate slope


D

“ Elastic demand” “ 富有弹性的需求”

P

QQ1

P1

Q2

P2

Q rises more than 10%

> 10%

10%> 1

Price elasticity

of demand

=% change in Q

% change in P=

P falls by 10%


D curve:

Elasticity:

relatively flat

relatively high

> 1


D

“ Perfectly elastic demand” (the other extreme) “ 完全有弹性的需求” ( 另一个极端例子 )

P

Q

P1

Q1

P changes by 0%

Q changes by any %

any %

0%= infinity

无穷大

Q2

P2 =Consumers’ price sensitivity:

D curve:

Elasticity:infinity

horizontal

extreme

Price elasticity

of demand

=% change in Q

% change in P=


Elasticity of a Linear Demand Curve 线性需求曲线的弹性

The slope of a linear demand curve is constant, but its elasticity is not.线性需求曲线的斜率为常数，但它的弹性不是常数

P

Q

$30

20

10

$00 20 40 60

200%40%

= 5.0E =

67%67%

= 1.0E =

40%200%

= 0.2E =


Price Elasticity and Total Revenue总收益与需求价格弹性

Continuing our scenario, if you raise your pricefrom $200 to $250, would your revenue rise or fall?

Revenue = P x Q

A price increase has two effects on revenue: Higher P means more

revenue on each unit you sell.

But you sell fewer units (lower Q), due to Law of Demand.

Which of these two effects is bigger? It depends on the price elasticity of demand.

继续我们的故事，如果你把价格从 $200上升到 $250，你的收益会增加还是减少？

收益 = P x Q 价格上升对收益有两种影响：

更高的价格意味着你在售出的每单位物品上会有更多的收益

但根据需求定理，你售出的物品数量会减少

两种影响哪种更大？这要取决于需求价格弹性


Price Elasticity and Total Revenue

If demand is elastic, then

price elast. of demand > 1

如果需求是有弹性的，那需求价格弹性 > 1

% change in Q > % change in P

需求量变动百分比 > 价格变动百分比The fall in revenue from lower Q is greater than the increase in revenue from higher P, so revenue falls.需求量减少使收益减少的幅度大于价格上升使收益增加的幅度，总收益减少

Revenue = P x Q


=Percentage change in Q




Elastic demand(elasticity = 1.8) P

Q

D$200

12

If P = $200, Q = 12 and revenue = $2400.

When D is elastic, a price increase causes revenue to fall.

$250

8

If P = $250, Q = 8 and revenue = $2000.

lost revenue due to lower Q

increased revenue due to higher P




If demand is inelastic, then

price elast. of demand < 1 % change in Q < % change in P

The fall in revenue from lower Q is smaller than the increase in revenue from higher P, so revenue rises.需求量减少使收益减少的幅度小于价格上升使收益增加的幅度，总收益增加

In our example, suppose that Q only falls to 10 (instead of 8) when you raise your price to $250.

Revenue = P x Q


=Percentage change in Q




Now, demand is inelastic: elasticity = 0.82 P

Q

D

$200

12

If P = $200, Q = 12 and revenue = $2400. $250

10

If P = $250, Q = 10 and revenue = $2500.When D is inelastic, a price increase causes revenue to rise.

lost revenue due to lower Q

increased revenue due to higher P


A C T I V E L E A R N I N G A C T I V E L E A R N I N G 22 Elasticity and expenditure/revenueElasticity and expenditure/revenue 弹性与支弹性与支出出 //收益收益A. Pharmacies raise the

price of insulin by 10%. Does total expenditure on insulin rise or fall?

B. As a result of a fare war, the price of a luxury cruise falls 20%. Does luxury cruise companies’ total revenue

rise or fall?

A. 药店将胰岛素的价格提高 10%，对胰岛素的总支出会增加还是减少？

B. 作为价格战的结果，游轮价格下降了 20%。游轮制造公司的收益会增加还是下降？

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AnswersAnswers

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A. Pharmacies raise the price of insulin by 10%. Does total expenditure on insulin rise or fall?

药店将胰岛素的价格提高 10%，对胰岛素的总支出会增加还是减少？

Expenditure = P x Q

Since demand is inelastic, Q will fall less than 10%, so expenditure rises.

胰岛素的需求缺乏弹性，需求量下降幅度不超过 10%，因此支出增加


AnswersAnswers

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B. As a result of a fare war, the price of a luxury cruise falls 20%. Does luxury cruise companies’ total revenue rise or fall?

作为价格战的结果，游轮价格下降了 20%。游轮制造公司的收益会增加还是下降？

Revenue = P x Q

The fall in P reduces revenue, but Q increases, which increases revenue. Which effect is bigger?

Since demand is elastic, Q will increase more than 20%, so revenue rises.


APPLICATION: Does Drug Interdiction Increase or Decrease Drug-Related Crime? 禁毒增加还是减少了与毒品相关的犯罪 One side effect of illegal drug

use is crime: Users often turn to crime to finance their habit.

We examine two policies designed to reduce illegal drug use and see what effects they have on drug-related crime.

For simplicity, we assume the total dollar value of drug-related crime equals total expenditure on drugs.

Demand for illegal drugs is inelastic, due to addiction issues.

使用毒品的一个不利影响是犯罪：吸毒上瘾的人往往会有暴力犯罪，以得到吸毒所需要的钱

我们比较两种旨在减少吸毒的政策，并观察它们对与毒品相关的犯罪的影响

为简化起见，我们假定与毒品相关的犯罪的美元价值等于购买毒品的总支出

由于吸毒成瘾，非法毒品的需求是缺乏弹性的


D1

Policy 1: Interdiction 禁毒

Price of Drugs

Quantity of Drugs

S1

S2

P1

Q1

P2

Q2

Interdiction reduces the supply of drugs.

Since demand for drugs is inelastic, P rises propor-tionally more than Q falls.

Result: an increase in total spending on drugs, and in drug-related crime 在毒品上的总支出和与毒品相关的犯罪都会增加

new value of drug-related crime与毒品相关的犯罪的新价值

initial value of drug-related crime


Policy 2: Education

Price of Drugs

Quantity of Drugs

D1

S

P1

Q1

D2

P2

Q2

Education reduces the demand for drugs.

P and Q fall.

Result:A decrease in total spending on drugs, and in drug-related crime.结果：在毒品上的总支出和与毒品相关的犯罪都减少

initial value of drug-related crime

new value of drug-related crime


Price Elasticity of Supply

Price elasticity of supply measures how much Qs responds to a change in P.

供给价格弹性衡量一种物品供给量对其价格变动反应程度的指标

Price elasticity of supply

=Percentage change in Qs


Loosely speaking, it measures sellers’ price-sensitivity.

Again, use the midpoint method to compute the percentage changes. 继续使用中点法计算变动的百分比


Q2

Price Elasticity of Supply

Price elasticity of supply equals

P

Q

S

P2

Q1

P1

P rises by 8%

Q rises by 16%

16%

8%= 2.0

Price elasticity of supply

=Percentage change in Qs


Example:


The Variety of Supply Curves The slope of the supply

curve is closely related to price elasticity of supply.

Rule of thumb: The flatter the curve, the bigger the elasticity. The steeper the curve, the smaller the elasticity.

Five different classifications.…

供给价格弹性与供给曲线的斜率密切相关

拇指规则：通过某一点的供给曲线越平坦，供给的价格弹性就越大通过某一点的供给曲线越陡峭，供给的价格弹性就越小

五种不同的分类 .…


S

“ Perfectly inelastic” (one extreme)

P

QQ1

P1

P2

Q changes by 0%

0%

10%= 0

Price elasticity

of supply

=% change in Q

% change in P=

P rises by 10%

Sellers’ price sensitivity:

S curve:

Elasticity:

vertical

none

0


S

“ Inelastic”

P

QQ1

P1

Q2

P2

Q rises less than 10%

< 10%

10%< 1

Price elasticity

of supply

=% change in Q

% change in P=

P rises by 10%


S curve:

Elasticity:

relatively steep

relatively low

< 1


S

“ Unit elastic”

P

QQ1

P1

Q2

P2

Q rises by 10%

10%

10%= 1

Price elasticity

of supply

=% change in Q

% change in P=

P rises by 10%


S curve:

Elasticity:

intermediate slope

intermediate

= 1


S

“ Elastic”

P

QQ1

P1

Q2

P2

Q rises more than 10%

> 10%

10%> 1

Price elasticity

of supply

=% change in Q

% change in P=

P rises by 10%


S curve:

Elasticity:

relatively flat

relatively high

> 1


S

“ Perfectly elastic” (the other extreme)

P

Q

P1

Q1

P changes by 0%

Q changes by any %

any %

0%= infinity

Price elasticity

of supply

=% change in Q

% change in P=

Q2

P2 =Sellers’ price sensitivity:

S curve:

Elasticity:

horizontal

extreme

infinity


The Determinants of Supply Elasticity

The more easily sellers can change the quantity they produce, the greater the price elasticity of supply. Example: Supply of

beachfront property is harder to vary and thus less elastic than supply of new cars.

For many goods, price elasticity of supply is greater in the long run than in the short run, because firms can build new factories, or new firms may be able to enter the market.

卖者越容易改变他们的生产数量，供给价格弹性越大例如：海滨别墅的供给较难改变，因此其供给弹性要低于新汽车的供给弹性

对许多物品而言，长期供给价格弹性都要大于短期供给价格弹性。这是因为企业在长期能建更多的工厂，或者新的企业能够进入市场


Elasticity and changes in Elasticity and changes in equilibriumequilibrium

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The supply of beachfront property is inelastic. The supply of new cars is elastic. 海滨别墅的供给缺乏弹性的，而新汽车的供给是富有弹性的

Suppose population growth causes demand for both goods to double (at each price, Qd doubles).假设人口数量的增长使对两种物品的需求都翻了一番（就是在在每种价格水平上，需求量加倍）

For which product will P change the most?哪种物品的价格变动更大？

For which product will Q change the most?哪种物品的产量变动更大？


AnswersAnswers

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Beachfront property 海滨别墅 (inelastic supply):

P

Q

D1S

Q1

P1 A

When supply is inelastic, an increase in demand has a bigger impact on price than on quantity.

供给缺乏弹性时，需求增加使价格上升的比例要大于产量增加的比例

D2

B

Q2

P2


AnswersAnswers

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New cars(elastic supply):

P

Q

D1

S

Q1

P1

A

When supply is elastic, an increase in demand has a bigger impact on quantity than on price.供给富有弹性时，需求增加使产量增加的比例要大于价格上升的比例

D2

Q2

P2

B


S

How the Price Elasticity of Supply Can Vary

供给价格弹性会如何变动P

Q

Supply often becomes less elastic as Q rises, due to capacity limits. 由于生产能力限制，当供给量越大时，供给价格弹性越小

Supply often becomes less elastic as Q rises, due to capacity limits. 由于生产能力限制，当供给量越大时，供给价格弹性越小

$15

525

12

500

$3

100

4

200

elasticity > 1

elasticity < 1


Other Elasticities Income elasticity of demand: measures the response of Qd to a

change in consumer income

需求收入弹性：衡量消费者收入变动时需求量如何变动

Income elasticity of demand

=Percent change in Qd

Percent change in income

Recall from Chapter 4: An increase in income causes an increase in demand for a normal good.

Hence, for normal goods, income elasticity > 0.

For inferior goods, income elasticity < 0.


Other Elasticities Cross-price elasticity of demand:

measures the response of demand for one good to changes in the price of another good

需求的交叉价格弹性：衡量一种物品需求量对另外一种物品价格变动的反应程度

Cross-price elast. of demand

=% change in Qd for good 1 % change in price of good 2

For substitutes, cross-price elasticity > 0 (e.g., an increase in price of beef causes an increase in demand for chicken)

For complements, cross-price elasticity < 0 (e.g., an increase in price of computers causes decrease in demand for software)


Cross-Price Elasticities in the News

“As Gas Costs Soar, Buyers Flock to Small Cars” -New York Times, 5/2/2008

“Gas Prices Drive Students to Online Courses” -Chronicle of Higher Education, 7/8/2008

“Gas prices knock bicycle sales, repairs into higher gear” -Associated Press, 5/11/2008

“Camel demand soars in India” (as a substitute for “gas-guzzling tractors”) -Financial Times, 5/2/2008

“High gas prices drive farmer to switch to mules” -Associated Press, 5/21/2008

“ 汽油价格上升，买者转而购买小排量汽车” - 纽约时报， 2008 年5月 2 日

“汽油价格上升，学生多选网上课程” -高等教育纪事， 2008 年 7月 8 日

“汽油价格影响到自行车销售” -美联社， 2008 年 5月 11 日

“骆驼在印度的需求大幅上升” （骆驼是耗油的拖拉机的替代品） - 金融时报， 2008 年5月 2 日

“高油价使农民更喜欢用骡子” -美联社， 2008 年 5月 21 日

CHAPTER SUMMARYCHAPTER SUMMARY Elasticity measures the

responsiveness of Qd or Qs to one of its determinants.

Price elasticity of demand equals percentage change in Qd divided by percentage change in P. When it’s less than one, demand is “inelastic.” When greater than one, demand is “elastic.”

When demand is inelastic, total revenue rises when price rises. When demand is elastic, total revenue falls when price rises.

弹性衡量需求量或供给量对其一个影响因素变动的反应程度

需求价格弹性衡量需求量对价格变动的反应程度。如果弹性小于 1，需求缺乏弹性；如果大于 1，需求富有弹性

对于缺乏弹性的需求曲线，其总收益随着价格的上升而增加。对于富有弹性的需求曲线，其总收益随着价格的上升而减少

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CHAPTER SUMMARYCHAPTER SUMMARY Demand is less elastic in the

short run, for necessities, for broadly defined goods, or for goods with few close substitutes.

Price elasticity of supply equals percentage change in Qs divided by percentage change in P. When it’s less than one, supply is “inelastic.” When greater than one, supply is “elastic.”

Price elasticity of supply is greater in the long run than in the short run.

如果某种物品没有相近的替代品，是必需品而不是奢侈品，市场范围大，或者是在短期内，那么，这种物品就更倾向于缺乏弹性

供给价格弹性衡量的是供给量对价格变动的反应程度。如果弹性小于 1，供给缺乏弹性。如果弹性大于 1，供给富有弹性

供给价格弹性在长期中比在短期中更富有弹性

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CHAPTER SUMMARYCHAPTER SUMMARY The income elasticity of

demand measures how much quantity demanded responds to changes in buyers’ incomes.

The cross-price elasticity of demand measures how much demand for one good responds to changes in the price of another good.

需求收入弹性衡量的是需求量对消费者收入变动的反应程度

需求的交叉价格弹性衡量一种物品需求量对另一种物品价格变动的反应程度

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Elasticity and its Application

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