🛒Principles of Microeconomics Unit 8 – Perfect Competition

Key Concepts

• Perfect competition a market structure characterized by many buyers and sellers, homogeneous products, free entry and exit, and perfect information
• Market equilibrium occurs when quantity supplied equals quantity demanded, resulting in a market-clearing price
• Profit maximization the primary goal of firms, achieved by producing at the quantity where marginal revenue equals marginal cost ($MR = MC$)
• Economic efficiency achieved when resources are allocated optimally, resulting in the maximum possible social welfare
  • Allocative efficiency occurs when the price of a good equals its marginal cost of production ($P = MC$)
  • Productive efficiency occurs when firms produce at the minimum of their average total cost curve ($ATC_{min}$)
• Consumer and producer surplus measures of economic welfare that represent the benefits to consumers and producers from participating in a market
• Pareto efficiency a state in which no one can be made better off without making someone else worse off

Market Structure Basics

• Market structures classified based on the number of firms, product differentiation, barriers to entry and exit, and information availability
  • Perfect competition, monopolistic competition, oligopoly, and monopoly are the four main market structures
• Number of firms in perfect competition, there are many small firms, each with an insignificant market share
• Product differentiation in perfect competition, firms sell homogeneous (identical) products
• Barriers to entry and exit in perfect competition, there are no barriers, allowing firms to freely enter or exit the market
• Information availability in perfect competition, all market participants have perfect information about prices, costs, and product quality

Characteristics of Perfect Competition

• Large number of buyers and sellers each individual buyer and seller has no influence on the market price
• Homogeneous products all firms sell identical products, making them perfect substitutes for each other
• Free entry and exit no barriers prevent new firms from entering the market or existing firms from leaving
• Perfect information all market participants have complete knowledge of prices, costs, and product quality
• Price-taking behavior firms and consumers are price takers, meaning they accept the market price as given and cannot influence it
• No externalities the production or consumption of goods does not result in uncompensated costs or benefits to third parties
• No government intervention the market operates without government interference, such as price controls, subsidies, or taxes

Supply and Demand in Perfect Markets

• Market supply curve derived by horizontally summing the individual supply curves of all firms in the market
  • In perfect competition, the market supply curve is the same as the individual firm's supply curve above the shutdown point
• Market demand curve represents the total quantity demanded by all consumers at each price level
• Equilibrium price and quantity determined by the intersection of the market supply and demand curves
  • At equilibrium, quantity supplied equals quantity demanded ($Q_s = Q_d$)
• Changes in supply and demand shifts in the supply or demand curves lead to changes in the equilibrium price and quantity
  • Factors that shift supply include input prices, technology, expectations, and the number of sellers
  • Factors that shift demand include income, preferences, prices of related goods, expectations, and the number of buyers

Firm Behavior and Decision Making

• Profit maximization firms aim to maximize their profits by choosing the optimal level of output
  • Profits calculated as total revenue minus total costs ($\pi = TR - TC$)
• Marginal analysis firms make decisions by comparing marginal revenue ($MR$) and marginal cost ($MC$)
  • Marginal revenue the change in total revenue from selling one additional unit ($MR = \frac{\Delta TR}{\Delta Q}$)
  • Marginal cost the change in total cost from producing one additional unit ($MC = \frac{\Delta TC}{\Delta Q}$)
• Shutdown point the minimum price at which a firm is willing to continue operating in the short run, equal to the minimum of the average variable cost curve ($AVC_{min}$)
• Break-even point the price at which a firm's total revenue equals its total costs, equal to the minimum of the average total cost curve ($ATC_{min}$)
• Long-run decision making in the long run, firms can adjust all inputs and make entry or exit decisions based on economic profits or losses

Short-Run vs. Long-Run Equilibrium

• Short run a period in which at least one input is fixed (usually capital), and firms can only adjust variable inputs like labor
  • In the short run, firms may earn economic profits or losses
• Long run a period in which all inputs are variable, and firms can enter or exit the market
  • In the long run, economic profits and losses are eliminated as firms enter or exit the market
• Short-run equilibrium occurs when each firm maximizes its profits by producing at the point where $MR = MC$
  • In perfect competition, $MR = P$, so firms produce where $P = MC$
• Long-run equilibrium occurs when there are no economic profits or losses, and firms produce at the minimum of their long-run average total cost curve ($LRATC_{min}$)
  • In perfect competition, long-run equilibrium implies $P = LRATC_{min} = LMC$

Efficiency and Market Outcomes

• Allocative efficiency in perfect competition, allocative efficiency is achieved in the long run as price equals marginal cost ($P = MC$)
  • This ensures that resources are allocated to their most valued uses
• Productive efficiency in perfect competition, productive efficiency is achieved in the long run as firms produce at the minimum of their average total cost curve ($ATC_{min}$)
  • This implies that firms are using the most cost-effective production methods
• Consumer and producer surplus in perfect competition, total economic welfare (the sum of consumer and producer surplus) is maximized
  • Consumer surplus the difference between what consumers are willing to pay and what they actually pay
  • Producer surplus the difference between what producers receive and their marginal costs
• Pareto efficiency perfect competition leads to a Pareto-efficient outcome, as no one can be made better off without making someone else worse off

Real-World Examples and Limitations

• Agricultural markets many agricultural markets, such as those for wheat, corn, and soybeans, exhibit characteristics close to perfect competition
  • Large number of buyers and sellers, homogeneous products, and relatively free entry and exit
• Financial markets some financial markets, like foreign exchange markets and stock markets, also resemble perfect competition
  • Many buyers and sellers, homogeneous assets, and perfect information (in theory)
• Limitations of perfect competition model real-world markets often deviate from the strict assumptions of perfect competition
  • Product differentiation, barriers to entry and exit, imperfect information, and externalities are common in practice
• Role of government intervention governments may intervene in markets to address market failures or achieve social objectives
  • Antitrust laws, regulations, taxes, and subsidies can alter market outcomes and efficiency
• Transition to other market structures over time, markets may evolve from perfect competition to other structures like monopolistic competition or oligopoly
  • Technological changes, economies of scale, and network effects can lead to increased market concentration and product differentiation