尼克尔森微观经济学课件中文版ch11

Quantity
17
Price Controls and Shortages 价格控制和短缺
Price
LS P3 P1
D’
This shaded triangle represents the value of additional consumer surplus that would have been attained without the price control 阴影三角形，表示了没有价格 控制时，所能得到的额外的消 费者剩余
P*
At outputs between Q1 and Q*, demanders would value an additional unit more than it would cost suppliers to produce 在Q1和Q*之间的产出水平 ，需求者对额外一个单位的评价比生 产者生产所花费的成本要高
D 3 4
Quantity
10
Welfare Loss Computations 计算福利损失
• The welfare loss will be shared by producers and consumers福利损失由生产者和消费者共同承担 • In general, it will depend on the price elasticity of demand and the price elasticity of supply to determine who bears the larger portion of the loss一般来说，由需求价格弹性 和供给价格弹性来决定谁承担较大部分的损失
D’
Q1
Q2
Quantity
15
Price Controls and Shortages 价格控制和短缺
Price
LS P3 P1
D’
Some buyers will gain because they can purchase the good for a lower price 一些买者会获利，因为他 们可以用较低的价格购买 商品 This gain in consumer surplus is the shaded Rectangle 消费者剩余的这一增加用 阴影长方形表示
D’
D
Q1
Quantity
13
Price Controls and Shortages 价格控制和短缺
Price
SS
In the short run, price rises to P2 在短期，价格上升至P2
LS
P2 P3 P1
Firms would begin to enter the industry 企业会开始进入行业 The price would end up at P3 价格最终为P3
Q1
Q2
Quantity
16
Price Controls and Shortages 价格控制和短缺
Price The gain to consumers is also a loss to producers who now receive a lower price 消费者的收益也是生产者的损失，生产者 现在接受的价格较低
[U (Q ) PQ] [PQ P (Q )dQ] U (Q ) P (Q )dQ
0 0 Q Q
• In long-run equilibria along the long-run supply curve, P(Q) = AC = MC 在长期均衡中，沿着长期供给曲线， P(Q) = AC = MC
• The area between the demand and the supply curve represents the sum of consumer and producer surplus 需求和供给曲线 之间的区域代表了消费者剩余和生产 者剩余之和
– measures the total additional value obtained by market participants by being able to make market transactions 衡量了市场参与者通过市场交易所获得的总的额外价值
– in the case of linear demand and supply curves, the calculation is simple because the areas of loss are often triangular 在线性需求和供给曲线情况下，计算很简单，因为损失的区 域常常为三角形
12
Price Controls and Shortages 价格控制和短缺
Price
SS
LS P1
Initially, the market is in long-run equilibrium at P1, Q1 初始市场均衡为P1, Q1 Demand increases to 需求增加至D’
8
Example：Welfare Loss Computations 例：计算福利损失
• Restriction of output to Q0 = 3 would create a gap between what demanders are willing to pay (PD) and what suppliers require (PS) 限制产出为Q0 = 3 ，会使消费者所 愿意支付的(PD)和供给者所要求的(PS)之间产生差距 PD = 10 - 3 = 7 PS = 2 + 3 = 5
Q1
Q2
Quantity
19
Price Controls and Shortages 价格控制和短缺
5
Economic Efficiency and Welfare Analysis 经济效率和福利分析
• Maximizing total surplus with respect to Q yields 对Q最大化总剩余，得到
U’(Q) = P(Q) = AC = MC
– maximization occurs where the marginal value of Q to the representative consumer is equal to market price 最大化的点发生在典型消费者的边际价值等于市场价格时 • the market equilibrium市场均衡
Q1
Q2
Quantity
18
Price Controls and Shortages 价格控制和短缺
Price
LS P3 P1
D’
This shaded triangle represents the value of additional producer surplus that would have been attained without the price control 阴影三角形，表示了没有 价格控制时，所能得到的 额外的生产者剩余
D
Quantity
Q1 Q*
4
Economic Efficiency and Welfare Analysis 经济效率和福利分析
• Mathematically, we wish to maximize数学上，我们希望 最大化总剩余
consumer surplus + producer surplus =
• This area is maximized at the competitive market equilibrium这一区域在竞争性市场均衡处最大化
2
Economic Efficiency and Welfare Analysis 经济效率和福利分析
Price
S
Consumer surplus is the area above price and below Demand 消费者剩余是价格之上需求之下的区域
– the side of the market with the smallest price elasticity (in abБайду номын сангаасolute value)价格弹性(绝对值）较小的一方
11
Price Controls and Shortages 价格控制和短缺
• Sometimes governments may seek to control prices at below equilibrium levels有时候，政府会把价格控制在 均衡水平之下
D’
D
Q1
Quantity
14
Price Controls and Shortages 价格控制和短缺
Price
LS P3 P1
Suppose that the government imposes a price ceiling at P1 假设政府施加价格上限P1 There will be a shortage equal toQ2 - Q1 短缺数量为Q2 - Q1
9
Example：Welfare Loss Computations 例：计算福利损失
Price
The welfare loss from restricting output to 3 is the area of a triangle 由限制产出为3而引起的福利损失为三角形的面积
S
7 6 5
The loss = (0.5)(2)(1) = 1 损失= (0.5)(2)(1) = 1
Chapter 11 第十一章
APPLIED COMPETITIVE ANALYSIS 应用竞争性分析
Copyright ©2005 by South-Western, a division of Thomson Learning. All rights reserved.
1
Economic Efficiency and Welfare Analysis 经济效率和福利分析
LS P3 P1
D’
The shaded rectangle therefore represents a pure transfer from producers to consumers 所以，阴影长方形代表了从生产者 向消费者的转移
No welfare loss there 这里没有福利损失
Q1 Q2
7
Example：Welfare Loss Computations 例：计算福利损失
• Suppose that the demand is given by假设需求为 QD = 10 - P
and supply is given by 供给为
QS = P - 2 • Market equilibrium occurs where P* = 6 and Q* = 4 市场均衡为 P* = 6 ，Q* = 4
6
Welfare Loss Computations 计算福利损失
• Use of consumer and producer surplus notions makes possible the explicit calculation of welfare losses caused by restrictions on voluntary transactions 使用消费者和生产者剩余的概念，可以对限制自愿交 易引起的福利损失进行明确的计算
P*
Producer surplus is the area below price and above supply 生产者剩余是价格之下供给之上的区域
D
Quantity
Q*
3
Economic Efficiency and Welfare Analysis 经济效率和福利分析
Price
S
At output Q1, total surplus will be smaller 在产出Q1，总剩余较小
– this will lead to a shortage这会导致短缺
• We can look at the changes in producer and consumer surplus from this policy to analyze its impact on welfare 我们可以通过计算这一政策中生产者和消费者剩余的 变化，来分析其对福利的影响