Microeconomics Exam 3 Study Guide: Market Structures, Oligopoly, and Market Power

Chapter 12: Perfect Competition and Allocative Efficiency

Perfect Competition: Assumptions and Outcomes

• Perfect Competition is a market structure characterized by many firms, identical products, and free entry and exit.

• Key assumptions include:

  • Many buyers and sellers

  • Homogeneous (identical) products

  • Perfect information

  • No barriers to entry or exit

• Firms are price takers, meaning they accept the market price as given.

Profit Maximization and Output Decision

• Firms maximize profit where Marginal Cost (MC) = Marginal Revenue (MR).

• In perfect competition, MR = Price (P).

• The shutdown condition occurs when Price < Average Variable Cost (AVC).

Productive and Allocative Efficiency

• Productive Efficiency: Firms produce at the lowest possible cost (where MC = ATC at its minimum).

• Allocative Efficiency: Resources are allocated such that P = MC, maximizing total surplus.

Profit, Loss, and Break-even Analysis

• Profit or loss is determined by comparing Price to Average Total Cost (ATC):

  • If P > ATC: Economic profit

  • If P = ATC: Break-even

  • If P < ATC: Economic loss

• Graphical analysis involves plotting cost curves and identifying profit/loss areas.

Example: A perfectly competitive firm faces a market price of $10, with ATC = $8 and AVC = $6 at the profit-maximizing output. The firm earns an economic profit of $2 per unit.

Chapter 13: Monopolistic Competition and Allocative Efficiency

Monopolistic Competition: Features and Comparison

• Monopolistic Competition is a market structure with many firms selling differentiated products and free entry/exit.

• Differs from perfect competition due to product differentiation and some price-setting power.

Profit, Loss, and Break-even in Monopolistic Competition

• Firms maximize profit where MR = MC.

• Short-run outcomes: profit, loss, or break-even possible.

• Long-run: Entry/exit drives profit to zero (firms earn normal profit).

Allocative Efficiency in Monopolistic Competition

• Monopolistic competition is not allocatively efficient because P > MC in equilibrium.

Example: A restaurant in a city offers a unique menu, differentiating itself from competitors, but in the long run, new restaurants enter, driving profits to zero.

Chapter 14: Oligopoly and Game Theory

Oligopoly: Structure and Measurement

• Oligopoly is a market structure with a few large firms, which may sell identical or differentiated products.

• Key features: interdependence, barriers to entry, potential for collusion.

• Concentration Ratios and the Herfindahl-Hirschman Index (HHI) measure market concentration.

Game Theory and Strategic Behavior

• Game theory analyzes strategic interactions among firms.

• Prisoner's Dilemma: A classic example where rational choices lead to suboptimal outcomes.

• Dominant Strategy: A strategy that is best regardless of what others do.

• Nash Equilibrium: A set of strategies where no player can benefit by unilaterally changing their strategy.

• Cooperative Equilibrium: Firms cooperate to maximize joint profits (e.g., cartels).

Example: Two firms in an oligopoly can choose to collude or compete. If both compete, they earn lower profits; if both collude, they earn higher profits, but there is an incentive to cheat.

Chapter 15: Market Power and Antitrust Policy

Market Power and Its Sources

• Market Power: The ability of a firm to set prices above marginal cost.

• Sources include product differentiation, barriers to entry, and control of key resources.

Pricing Strategies and Discrimination

• Price Discrimination: Charging different prices to different consumers for the same product.

• Types:

  • First-degree (perfect) price discrimination

  • Second-degree (quantity discounts)

  • Third-degree (by consumer group)

• Vertical vs. Horizontal Mergers: Vertical mergers combine firms at different production stages; horizontal mergers combine competitors.

Antitrust Policy and Regulation

• Antitrust laws prevent anti-competitive practices and promote competition.

• Key legislation: Sherman Act, Clayton Act.

• Regulatory tools include the Herfindahl-Hirschman Index (HHI) for merger analysis.

Example: The Department of Justice uses the HHI to evaluate whether a proposed merger will significantly reduce competition in an industry.

Table: Comparison of Market Structures

Market Structure	Number of Firms	Product Type	Entry Barriers	Market Power	Long-Run Profit
Perfect Competition	Many	Identical	None	None	Zero
Monopolistic Competition	Many	Differentiated	Low	Some	Zero
Oligopoly	Few	Identical or Differentiated	High	Significant	Possible
Monopoly	One	Unique	Very High	Complete	Possible

Additional info: This guide expands on the listed study concepts by providing definitions, examples, and a comparative table for clarity. Students should refer to their textbook for detailed graphs and further applications.