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Market Structures and Revenue Curves

Aug 10, 2025

Overview

This lecture explains the differences between perfect and imperfect competition, focusing on how firms in imperfectly competitive markets face unique demand and marginal revenue curves.

Types of Market Structures

  • Perfect competition has many firms producing identical products with no barriers to entry.
  • Firms in perfect competition are price takers; market price equals marginal revenue.
  • Monopoly exists when one firm dominates the market with significant entry barriers.
  • Monopolistic competition features many firms with differentiated products and some entry barriers.
  • Athletic shoe companies like Nike and Adidas are examples of monopolistic competition.

Demand and Marginal Revenue in Imperfect Competition

  • In imperfect competition, each firm faces its own downward-sloping demand curve due to differentiation.
  • Increasing production lowers the price for all units sold, not just the last one.
  • Marginal revenue (MR) is less than price for additional units beyond the first.
  • MR is calculated as the change in total revenue divided by the change in quantity.
  • When price drops for all units sold, MR can be much lower than price, and may become negative if total revenue decreases.
  • The MR curve in imperfect competition is downward sloping and steeper than the demand curve.

Comparing Marginal Revenue Curves

  • In perfect competition, the MR curve is horizontal (equal to market price).
  • In imperfect competition, the MR curve slopes downward faster than the demand curve due to price effects on all units sold.

Key Terms & Definitions

  • Perfect Competition — market structure with many firms selling identical products and no barriers to entry.
  • Imperfect Competition — market structures where firms have some control over price due to product differentiation or other factors.
  • Monopolistic Competition — many firms compete with differentiated products and some barriers to entry.
  • Monopoly — a single firm controls the entire market and faces the market demand curve.
  • Marginal Revenue (MR) — the additional revenue gained from selling one more unit of a product.
  • Demand Curve — shows the relationship between the quantity demanded and the price.

Action Items / Next Steps

  • Practice calculating total and marginal revenue for firms in imperfect competition.
  • Review the differences between demand and marginal revenue curves in various market structures.