Overview
This lesson compares perfectly competitive and imperfect markets (monopoly, monopolistic competition, oligopoly), focusing on the concepts of economic profit, normal profit, and economic loss using graphs.
Market Structures Overview
- Four key market structures: perfect competition, monopoly, monopolistic competition, and oligopoly.
- Perfect competition has many firms selling identical products; others have product differentiation or fewer firms.
Economic Profit Explained
- Economic profit is when average revenue (AR) is greater than average cost (AC).
- In graphs, economic profit per unit = AR - AC; total profit = (AR - AC) × quantity.
- In perfect competition, the demand curve is horizontal (perfectly elastic).
- Firms maximize profit where marginal cost (MC) intersects marginal revenue (MR).
- Typical example: farmers in a perfect market, fast food outlets in monopolistic competition, network providers in oligopoly.
Economic Profit in Imperfect Markets
- Monopoly: Demand curve is downward sloping; profit is where AR > AC.
- Oligopoly: Kinked demand curve; few firms; profit determined similarly (AR > AC).
- Monopolistic competition: Differentiated products; profit if AR > AC.
Normal Profit
- Normal profit occurs when AR = AC; the firm covers all costs but earns no extra profit.
- All four market structures can have normal profit situations.
- Firms earning normal profit stay in the market as they have no incentive to exit.
Economic Loss
- Economic loss occurs when AR < AC; firm’s revenue is less than costs.
- In this case, whether a firm should continue depends on average variable cost (AVC), not just AC.
- Without AVC information, it’s unclear if the firm should shut down.
- Applies to all market structures: perfect competition, monopoly, oligopoly, monopolistic competition.
Key Terms & Definitions
- Economic Profit — Profit when a firm's average revenue exceeds average cost (AR > AC).
- Normal Profit — Zero economic profit; AR equals AC.
- Economic Loss — Occurs when average revenue is less than average cost (AR < AC).
- Perfect Competition — Market with many firms selling identical products.
- Monopoly — One firm dominates, downward sloping demand.
- Oligopoly — Few firms, kinked demand curve.
- Monopolistic Competition — Many firms selling differentiated products.
- Marginal Cost (MC) — Cost of producing one more unit.
- Marginal Revenue (MR) — Revenue gained from selling one more unit.
- Average Revenue (AR) — Revenue per unit sold.
- Average Cost (AC) — Cost per unit produced.
- Average Variable Cost (AVC) — Variable cost per unit produced.
Action Items / Next Steps
- Review summary of market characteristics in the next part of the lesson.
- Practice drawing and labeling market structure graphs.
- Understand the relationship between AR, AC, and firm decisions.