Competitive Markets: Theory and Application (Microeconomics Chapter 9 Study Notes)

Chapter 9: Competitive Markets

9.1 Market Structure and Firm Behaviour

Understanding market structure is essential for analyzing how firms behave and perform in different competitive environments. Market structure encompasses the characteristics of a market that influence firm actions and outcomes.

• Market Structure: Refers to features such as the number and size of sellers, product differentiation, freedom of entry and exit, and the extent of knowledge about competitors.

• Market Power: The ability of a firm to influence the price of its product. Firms with market power can set prices above competitive levels.

• Competitive Market: A market where firms have little or no market power. The more market power firms possess, the less competitive the market is.

• Perfectly Competitive Market: The extreme case where each firm has zero market power.

Competitive Behaviour

Competitive behaviour describes how actively firms compete for customers, which may differ from the overall competitiveness of the market.

• Competitive Behaviour: The degree to which firms vie for business.

• Example 1: MasterCard and Visa compete actively, but their market is not perfectly competitive.

• Example 2: Wheat farmers do not compete actively, but their market is highly competitive.

9.2 The Theory of Perfect Competition

Perfect competition is a theoretical market structure characterized by several key assumptions that ensure no single firm can influence market price.

• Homogeneous Product: All firms sell identical products.

• Perfect Information: Customers know the product and prices offered by each firm.

• Small Firm Size: Each firm's minimum efficient scale is small relative to total industry output.

• Freedom of Entry and Exit: Firms can freely enter or exit the industry.

Demand Curve in Perfect Competition

The demand curve faced by a competitive industry slopes downward, while the demand curve for an individual firm is perfectly elastic (horizontal).

• Industry Demand Curve: Downward sloping due to the law of demand.

• Firm Demand Curve: Horizontal at the market price, indicating the firm is a price taker.

Why Small Firms Are Price Takers

• Individual firms' output changes have negligible effects on market price.

• Thus, firms face horizontal demand curves and must accept the market price.

Total, Average, and Marginal Revenue

Revenue concepts are crucial for understanding firm decision-making in competitive markets.

• Total Revenue (TR): The total amount received from sales. $TR = p \times Q$

• Average Revenue (AR): Revenue per unit sold. $AR = \frac{TR}{Q} = p$

• Marginal Revenue (MR): Change in total revenue from selling one more unit. $MR = \frac{\Delta TR}{\Delta Q} = p$

• For a price-taking firm: $p = AR = MR$

9.3 Short-Run Decisions

In the short run, firms aim to maximize profits, but may face losses depending on market conditions.

• Profit Maximization: $\pi = TR - TC$

• If $TR < TC$, the firm incurs economic losses ($\pi < 0$).

• Key questions: Should the firm produce at all? If so, how much?

Should the Firm Produce at All?

• If the firm shuts down, $\pi = -TFC$ (total fixed costs).

• If producing, must pay $TFC$ and incur $TVC$ (total variable costs).

• Produce if $TR > TVC$ or $p > AVC$ (average variable cost).

• If $TR < TVC$ or $p < AVC$, shut down to minimize losses.

• Shut-down Price: $p = \min AVC$

How Much Should the Firm Produce?

• Produce where marginal revenue equals marginal cost: $MR = MC$

• For competitive firms, $p = MR = MC$

Short-Run Supply Curve

• A competitive firm's supply curve is its $MC$ curve above the $AVC$ curve.

Industry Supply Curve

• The industry supply curve is the horizontal sum of all firms' $MC$ curves above $AVC$.

Short-Run Equilibrium

• Occurs when quantity demanded equals quantity supplied and each firm maximizes profit at the market price.

• Firms may make losses, break even, or earn profits.

Alternative Short-Run Profits

Case	Condition	Outcome
Losses	$MC = MR = p_1 < ATC$	Negative economic profit
Break-even	$MC = MR = p_2 = ATC$	Zero economic profit
Profits	$MC = MR = p_3 > ATC$	Positive economic profit

9.4 Long-Run Decisions

Long-run decisions involve entry and exit, which drive the market toward equilibrium where firms earn zero economic profit.

• Entry: Positive profits attract new firms, increasing supply and lowering price.

• Exit: Losses cause firms to leave, decreasing supply and raising price.

• Entry and exit continue until all firms just cover their total costs.

Long-Run Equilibrium

• Firms earn zero economic profit (break-even).

• Break-even Price: The price at which all costs, including opportunity cost of capital, are covered.

• Conditions for equilibrium:

  • Firms maximize profits given their capital ($MC = p$).

  • No firm is suffering losses or earning profits.

  • Firms cannot increase profits by changing plant size; each operates at minimum $LRAC$.

Short-Run vs. Long-Run Profit Maximization

• Short-run: Firms may not operate at minimum $LRAC$.

• Long-run: All firms operate at minimum $LRAC$.

Changes in Technology

• Technological improvements lower costs for new plants, leading to economic profits and entry.

• Industry output expands, price falls to new $SRATC$.

• Old technology plants may exit due to losses.

Declining Industries

• Continuous decrease in demand leads to industry decline.

• Obsolete equipment is typically a result, not a cause, of industry decline.

Historical Example: Whales and Crude Oil

• Whale oil demand declined due to rising costs and substitutes (kerosene).

• Crude oil faces similar pressures from rising extraction costs and alternative energy sources.

Additional info: These notes expand on the textbook slides by providing definitions, formulas, and context for key microeconomic concepts relevant to competitive markets.