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NotesEconomics HLTopic 2.11Oligopoly and game theory (HL)
Back to Economics HL Topics
2.11.81 min read

Oligopoly and game theory (HL)

IB Economics • Unit 2

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Contents

  • Oligopoly characteristics and interdependence
  • Game theory and the prisoner's dilemma
  • Collusion, cartels and the kinked demand curve

🤝 Oligopoly: The Few Dominate

Definition: Oligopoly.

Key characteristics

  • Few dominant firms — high concentration ratio (e.g. top 4 firms control 60%+ of the market).
  • High barriers to entry — economies of scale, brand loyalty, patents, sunk costs.
  • Strategic interdependence.
  • Products may be homogeneous or differentiated — oil (homogeneous), cars (differentiated).
  • Price rigidity — oligopolists tend to keep prices stable, competing instead through non-price methods.
Real-world examples: Airlines, smartphone manufacturers (Apple/Samsung), social media platforms, oil producers (OPEC), supermarkets, automobile manufacturers.

🎲 Game Theory and the Prisoner's Dilemma

Game theory: Game theory.

The prisoner's dilemma

Two firms choose between colluding (high price) and competing (low price). Each firm has an incentive to 'cheat' on the agreement — but if both cheat, both are worse off.

  • Both collude (high price): BEST joint outcome — both earn high profits.
  • One cheats (undercuts): the cheater gains market share; the colluder loses.
  • Both cheat (low price): WORST joint outcome — price war, both earn low profits.
  • The dominant strategy for each firm is to cheat (compete) — even though mutual collusion would make both better off.
  • The Nash equilibrium is where both firms compete — neither can improve by changing strategy alone.
Nash equilibrium.

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Related Economics HL Topics

Continue learning with these related topics from the same unit:

2.1.1The law of demand
2.1.2Determinants of demand
2.1.3Movements vs shifts of demand
2.1.4Linear demand functions (HL)
View all Economics HL topics

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IB Exam Questions on Oligopoly and game theory (HL)

Practice with IB-style questions filtered to Topic 2.11.8. Get instant AI feedback on every answer.

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How Oligopoly and game theory (HL) Appears in IB Exams

Examiners use specific command terms when asking about this topic. Here's what to expect:

Define

Give the precise meaning of key terms related to Oligopoly and game theory (HL).

AO1
Describe

Give a detailed account of processes or features in Oligopoly and game theory (HL).

AO2
Explain

Give reasons WHY — cause and effect within Oligopoly and game theory (HL).

AO3
Evaluate

Weigh strengths AND limitations of approaches in Oligopoly and game theory (HL).

AO3
Discuss

Present arguments FOR and AGAINST with a balanced conclusion.

AO3

See the full IB Command Terms guide →

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2.11.7Monopolistic competition (HL)
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Price discrimination (HL)2.11.9

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