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장 선 구(웅지세무대학)
© 2007 Worth Publishers Essentials of Economics Krugman • Wells • Olney
chapter
이 장에서는 불완전 경쟁시장에 대해서 학습한다.
이러한 시장의 대표적인 예로는 과점시장과 독점적 경쟁
시장이 있다.
불완전 경쟁시장을 분석하는 대표적인 방법은 게임이론을 들
수 있다.
일회성 게임과 반복게임을 통해서 기본적인 게임이론의 내용을
학습할 수 있다.
그리고 우리의 삶에 가장 밀접한 관련성이 있는 독점적
경쟁시장에 대해서도 학습할 것이다. 지역 몰에서의 푸드
코드가 대표적이다.
또한 진입과 퇴출, 그리고 효율성 관련 사항들, 광고에
대해서도 학습한다.
© 2007 Worth Publishers Essentials of Economics Krugman • Wells • Olney
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The law catches up with a colluding
oligopolist.
What you will learn in
this chapter:
➤ The meaning of oligopoly, and why it
occurs
➤ How our understanding of oligopoly can
be enhanced by using game theory,
especially the concept of the prisoners’
dilemma
➤ How repeated interactions among
oligopolists can help them achieve tacit
collusion
➤ How oligopoly works in practice, under
the legal constraints of antitrust policy
➤ How prices and profits are determined in
monopolistic competition in the short
run and the long run
➤ Why oligopolists and monopolistically
competitive firms differentiate their
products
➤ The economic significance of
advertising and brand names
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Oligopoly
An oligopoly is an industry with only a
small number of producers. A producer
in such an industry is known as an
oligopolist.
When no one firm has a monopoly, but
producers nonetheless realize that they
can affect market prices, an industry is
characterized by imperfect competition.
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Oligopoly
Understanding Oligopoly
An oligopoly consisting of only two firms
is a duopoly. Each firm is known as a
duopolist.
Sellers engage in collusion when they
cooperate to raise each others’ profits.
A cartel is an agreement by several
producers that increases their combined
profits by telling each one how much to
produce.
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Oligopoly
Understanding Oligopoly
When the decisions of two or more
firms significantly affect each others’
profits, they are in a situation of
interdependence.
The study of behavior in situations of
interdependence is known as game
theory.
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Oligopoly
The Prisoners’ Dilemma
The reward received by a player in a
game, such as the profit earned by an
oligopolist, is that player’s payoff.
A payoff matrix shows how the payoff
to each of the participants in a twoplayer game depends on the actions of
both. Such a matrix helps us analyze
interdependence.
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Oligopoly
The Prisoners’ Dilemma
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Oligopoly
The Prisoners’ Dilemma
Prisoners’ dilemma is a game based
on two premises: (1) Each player has
an incentive to choose an action that
benefits him or herself at the other
player’s expense. (2) When both
players act in this way, both are worse
off than if they had chosen different
actions.
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Oligopoly
The Prisoners’ Dilemma
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Oligopoly
The Prisoners’ Dilemma
An action is a dominant strategy when
it is a player’s best action regardless of
the action taken by the other player.
A Nash equilibrium, also known as a
noncooperative equilibrium, is the
result when each player in a game
chooses the action that maximizes his
or her payoff given the actions of other
players, ignoring the effects of his or her
action on the payoffs received by those
other players.
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Oligopoly
Overcoming the Prisoners’ Dilemma:
Repeated Interaction and Tacit Collusion
A firm engages in strategic behavior
when it attempts to influence the future
behavior of other firms.
A strategy of tit for tat involves playing
cooperatively at first, then doing
whatever the other player did in the
previous period.
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Oligopoly
Overcoming the Prisoners’ Dilemma:
Repeated Interaction and Tacit Collusion
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Oligopoly
Overcoming the Prisoners’ Dilemma:
Repeated Interaction and Tacit Collusion
When firms limit production and raise
prices in a way that raises each others’
profits, even though they have not
made any formal agreement, they are
engaged in tacit collusion.
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economics in action
The Rise and Fall and Rise of OPEC
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Oligopoly in Practice
The Legal Framework
Antitrust policy refers to the efforts of
the government to prevent oligopolistic
industries from becoming or behaving
like monopolies.
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Oligopoly in Practice
Tacit Collusion and Price Wars
Large Numbers
Complex Products and Pricing Schemes
Differences in Interests
Bargaining Power of Buyers
A price war occurs when tacit collusion
breaks down and prices collapse.
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Monopolistic Competition
Monopolistic competition is a market
structure in which there are many
competing producers in an industry,
each producer sells a differentiated
product, and there is free entry into and
exit from the industry in the long run.
Large Numbers
Differentiated Products
Free Entry Into and Exit From the Industry in the
Long Run
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Monopolistic Competition
Monopolistic Competition in the Short Run
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Monopolistic Competition
Monopolistic Competition in the Long Run
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Monopolistic Competition
Monopolistic Competition in the Long Run
In the long run, a monopolistically
competitive industry ends up in zeroprofit equilibrium: each firm makes
zero profit at its profit-maximizing
quantity.
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Monopolistic Competition
Monopolistic Competition in the Long Run
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Product Differentiation
Firms engage in product differentiation
when they try to convince buyers that
their product is different from the products
of other firms in the industry.
There are three important forms of product
differentiation:
■ differentiation by style or type
■ differentiation by location
■ differentiation by quality
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Product Differentiation
Controversies about Product Differentiation
The Role of Advertising
Advertising is worthwhile only in industries
in which firms have at least some market
power.
Given that advertising “works,” it’s not hard
to see why firms with market power would
spend money on it.
The big question about advertising is why it
works. A related question is whether
advertising is, from society’s point of view, a
waste of resources.
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Product Differentiation
Brand Names
A brand name is a name owned by a
particular firm that distinguishes its
products from those of other firms.
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KEY TERMS
Oligopoly
Oligopolist
Imperfect competition
Duopoly
Duopolist
Collusion
Cartel
Interdependence
Game theory
Payoff
Payoff matrix
Prisoners’ dilemma
Dominant strategy
Nash equilibrium
Noncooperative equilibrium
Strategic behavior
Tit for tat
Tacit collusion
Antitrust policy
Price war
Monopolistic competition
Zero-profit equilibrium
Product differentiation
Brand name
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