Chap_17垄断竞争(经济学原理,曼昆,中英文双语)

Many Sellers
There are many firms competing for the same group of customers.
uProduct examples include books, CDs, movies, computer games, restaurants, piano lessons, cookies, furniture, etc.
利润最大化产量
需求 产量
Monopolistic Competition in the Short Run
Short-run economic losses encourage firms to exit the market. This:
u Decreases the number of products offered. u Increases demand faced by the remaining
u Monopolistic Competition
u Many firms selling products that are similar but not identical.
u Oligopoly
u Only a few sellers, each offering a similar or identical product to the others.
Free Entry or Exit
u Firms can enter or exit the market without restriction.
u The number of firms in the market adjusts until economic profits are zero.
不完全竞争市场的类型
u 垄断竞争
u 许多出售相似但不相同产品的企业组成的 市场结构。
u 寡头
u 只有很少卖者，出售相似或相同的产品。
Monopolistic Competition 垄断竞争
Markets that have some features of competition and some features of
fall, and their profits decline.
短期中的垄断竞争企业
短期 经济利润激励新企业进入市场。这种 进入
u 增加了顾客可以选择的产品数量。 u 减少了市场已有的每家企业面临的需求。 u 使市场已有企业面临的需求曲线向左移动。 u 市场已有企业的产品需求减少，利润下降。
Figure 1 Monopolistic Competition in the Short Run
企业进入或退出的过程一直持续到市 场中的企业的经济利润正好是零时。
Figure 2 A Monopolistic Competitor in the Long Run
Price
MC ATC
P = ATC
MR
0 Profit-maximizing quantity
Demand
Quantity
图2. 长期中的垄断竞争者
quantity
Demand
Quantity
图1. 短期中的垄断竞争企业
价格
平均 总成本
价格
(b) 企业亏损
亏损
MC ATC
MR
0 利润最小化产量
需求 产量
The Long-Run Equilibrium 长期均衡
Firms will enter and exit until the firms are making exactly zero economic profits.
市场结构的四种类型
企业数量?
许多企业
一家 企业
几家 企业
有差别产量
产品类型？
相同产品
垄断 （15章）
寡头 （16章）
垄断竞争 （17章）
完全竞争 （14章）
• 自来水 • 有线电视
• 网球 • 原油
•小说 • 电影
• 小麦 • 牛奶
Types of Imperfectly Competitive Markets
动。 u 使继续留在市场中的企业的利润增加。
Figure 1 Monopolistic Competitors in the Short Run
Price Losses
(b) Firm Makes Losses
MC ATC
Average total cost
Price
MR
0
Loss-
minimizing
curve)
Quantity produced = Efficient scale
Quantity
图3. 垄断竞争与完全竞争
Monopolistic Competition
垄断竞争
Chapter 17
Monopolistic Competition
垄断竞争
n Imperfect competition refers to those market structures that fall between perfect competition and pure monopoly. 不完全竞争是指介于完全竞争与纯垄断 之间的市场结构。
ä There is excess capacity in monopolistic competition in the long run.
ä In monopolistic competition, output is less than the efficient scale of perfect competition.
Oligopoly (Chap16)
Monopolistic Competition
(Chap17)
Perfect Competition
（Chap14）
• Tap water • Cable TV
• Tennis balls • Crude oil
• Novels • Movies
• Wheat • Milk
firms. u Shifts the remaining firms’ demand curves
to the right. u Increases the remaining firms’ profits.
短期中的垄断竞争企业
短期经济亏损激励企业退出市场。随着 企业退出：
u 顾客可选择的产品数量少了。 u 增加了继续留在市场中的企业面临的需求。 u 使继续留在市场中的企业的需求曲线向右移
• The downward-sloping demand curve makes marginal revenue less than price.
ä As in a competitive market, price equals average total cost.
• Free entry and exit drive economic profit to zero.
monopoly. 有某些竞争特点又有某些垄断特点的
市场结构。
Attributes of Monopolistic competition 垄断竞争的特点
u Many sellers 很多卖者
u Product differentiation 产品有差异
u Free entry and exit 自由进入和退出
There are two noteworthy differences between monopolistic and perfect competition—excess
capacity and markup.
垄断竞争与完全竞争
垄断竞争和完全竞争之间有两个值 得注意的差别—过剩生产能力 和
价格加成。
u Rather than being a price taker, each firm faces a downward-sloping demand curve.
产品差异化
u 每个企业生产的一种产品至少与其 他企业生产的这种产品略有不同。
u 每个企业不是价格接受者，而是面 临一条向右下方倾斜的需求曲线。
很多卖者
有许多企业争夺同样的顾客群体。
u产品例子包括书籍、CD、电影、电脑游 戏、餐馆、钢琴课、点心、家居等等。
Product Differentiation
u Each firm produces a product that is at least slightly different from those of other firms.
Price
(a) Firm Makes Profit
MC ATC
Price
Average total cost
Profit
MR
0
Profit-
maximizing
quantity
Demand Quantity
图1. 短期中的垄断竞争企业
(a) 企业有利润
价格
MC ATC
价格 平均 总成本
利润
0
MR
自由进入或退出
u 企业可以没有限制地进入或退出一 个市场。
u 市场上企业的数量要一直调整到经 济利润为零时为止。
Monopolistic Competition in the Short Run
Short-run economic profits encourage new firms to enter the market. This:
Price
(a) Monopolistically Competitive Firm MC ATC
Price
P P = MC
MR百度文库
Demand
0
Quantity Efficient
produced scale
Quantity
0
(b) Perfectly Competitive Firm
MC ATC
P = MR (demand
长期均衡
n 两个特点
ä 正如在垄断市场上一样，价格大于边际成 本。
• 利润最大化要求边际收益等于边际成本。 • 向右下方倾斜的需求曲线使边际成本小于价格
。
ä 正如在竞争市场上一样，价格等于平均总 成本。
• 自由进入与退出使经济利润为零。
Monopolistic versus Perfect Competition
价格
MC ATC
P=ATC
MR
0 利润最大化产量
需求
产量
Long-Run Equilibrium
n Two Characteristics
ä As in a monopoly, price exceeds marginal cost.
• Profit maximization requires marginal revenue to equal marginal cost.
垄断竞争与完全竞争
n 过剩生产能力
ä 在长期中，完全竞争企业没有过剩生产能力。 ä 竞争市场上的自由进入使企业生产平均总成本最
小的产量，即企业的有效规模产量。 ä 在长期中，垄断竞争企业存在过剩生产能力。 ä 垄断竞争企业的产量低于完全竞争企业生产的有
效规模产量。
Figure 3 Monopolistic versus Perfect Competition
The Four Types of Market Structure
Number of Firms?
One firm
Few firms
Many firms
Type of Products?
Differentiated products
Identical products
Monopoly （Chap15）
Monopolistic versus Perfect Competition
n Excess Capacity
ä There is no excess capacity in perfect competition in the long run.
ä Free entry results in competitive firms producing at the point where average total cost is minimized, which is the efficient scale of the firm.
u Increases the number of products offered. u Reduces demand faced by firms already in
the market. u Incumbent firms’ demand curves shift to the
left. u Demand for the incumbent firms’ products