Chapter 9: The Analysis of Competitive Markets – Microeconomics Study Notes

Chapter 9: The Analysis of Competitive Markets

Introduction

This chapter applies supply and demand analysis to evaluate the effects of various government policies and market interventions. It focuses on consumer and producer surplus, market efficiency, and the impact of price controls, quotas, tariffs, and subsidies on competitive markets.

9.1 Evaluating the Gains and Losses from Government Policies—Consumer and Producer Surplus

Review of Consumer and Producer Surplus

• Consumer Surplus: The difference between what consumers are willing to pay for a good and what they actually pay. It is represented by the area between the demand curve and the market price.

• Producer Surplus: The difference between the market price and the minimum price at which producers are willing to sell. It is the area between the supply curve and the market price.

• Total Surplus: The sum of consumer and producer surplus, measuring the total welfare benefit in a competitive market.

• Example: If Consumer A values a good at $10 and the market price is $5, their surplus is $5. If Consumer B values it at $7, their surplus is $2. Consumer C, who values it at $5, has zero surplus.

Application of Surplus Concepts

• Welfare Effects: Government policies can create gains and losses for consumers and producers, altering total surplus.

• Deadweight Loss: The net loss of total surplus due to market inefficiencies, such as price controls or taxes.

• Formula: Deadweight loss is the area between the supply and demand curves that is lost due to intervention.

Price Controls and Elasticity

• Price Controls: When the government sets a maximum or minimum price, it can create shortages or surpluses.

• Inelastic Demand: If demand is inelastic, consumers may suffer a net loss from price controls, as the loss in surplus can outweigh the gains.

Example: Price Controls and Natural Gas Shortages

• Supply Equation: $Q_s = 15.90 + 0.72P$

• Demand Equation: $Q_d = 20.02 - 1.8P$

• Market-clearing price: $6.40$ per mcf; price control at $3.00$ per mcf creates a shortage.

• Surplus Calculations:

  • Consumer gain: $A = (20.6 ext{ billion mcf}) imes (3.40 ext{ / mcf}) = 70.04$ billion

  • Producer loss: $B = (1/2) imes (2.4 ext{ billion mcf}) imes (1.33 ext{ / mcf}) = 1.60$ billion

  • Deadweight loss: $C = (1/2) imes (2.4 ext{ billion mcf}) imes (3.40 ext{ / mcf}) = 4.08$ billion

9.2 The Efficiency of a Competitive Market

Economic Efficiency and Market Failure

• Economic Efficiency: Achieved when aggregate consumer and producer surplus is maximized.

• Market Failure: Occurs when unregulated markets do not provide proper signals, leading to inefficiency. Causes include externalities and lack of information.

• Externality: An action by a producer or consumer that affects others but is not reflected in market prices (e.g., pollution).

• Lack of Information: Consumers may not have enough information to make utility-maximizing decisions, justifying government intervention.

Welfare Loss from Price Controls

• When price is regulated above the market-clearing level, only a lower quantity is demanded, and deadweight loss occurs.

• Deadweight loss is represented by the area of triangles B and C in the supply-demand diagram.

Example: The Market for Human Kidneys

• Supply Curve: $Q^s = -16,000 + 0.4P$

• Demand Curve: $Q^d = 32,000 - 0.4P$

• At $P = 20,000$, supply elasticity is 0.33; demand elasticity is -0.33.

• Government intervention (setting price to zero) reduces supply and creates welfare loss for both suppliers and consumers.

9.3 Minimum Prices

Price Minimums and Minimum Wage

• Price Minimum: Government sets a minimum price ($P_{min}$) above equilibrium. Producers want to supply more than consumers will buy, resulting in unsold goods.

• Surplus Calculations:

  • Change in consumer surplus: $riangle CS = A - B$

  • Change in producer surplus: $riangle PS = A - C - D$

• Minimum Wage: Setting a wage floor ($W_{min}$) above equilibrium ($W_0$) creates unemployment ($L_2 - L_1$) and deadweight loss (triangles B and C).

Example: Airline Regulation

• Airline deregulation led to increased competition, lower prices, and industry changes.

• Regulation caused airlines to supply more than consumers demanded, resulting in unsold output and welfare losses.

• Profit margins fluctuated post-deregulation as competition increased and seat capacity was reduced.

Year	Number of U.S. carriers	Passenger Load Factor (%)	Real Cost Index (1995=100)
1975	36	54.0	101
1990	20	62.8	145
2015	12	84.1	82

9.4 Price Supports and Production Quotas

Price Supports

• Price Support: Government sets a price above equilibrium and buys excess supply to maintain it.

• Surplus Calculations:

  • Gain to producers: $A + B + D$

  • Loss to consumers: $A + B$

  • Cost to government: $(Q_2 - Q_1)P_s$

Production Quotas

• Government restricts supply to maintain a higher price, either by quotas or financial incentives.

• Cost to government must be at least $B + C + D$.

Incentive Programs

• Farmers receive payments to reduce output, increasing prices and reducing consumer surplus.

• Welfare Calculation: $A - B + A + B + D - B - C = A + D - B - C$

Example: Supporting the Price of Wheat

• 1981 Supply: $Q_s = 1800 + 240P$

• 1981 Demand: $Q_d = 3550 - 266P$

• Government buys 122 million bushels to raise price from $3.46 to $3.70 per bushel.

• Total cost: $1,075$ million; gain to producers: $638$ million.

9.5 Import Quotas and Tariffs

Definitions and Effects

• Import Quota: Limit on the quantity of a good that can be imported.

• Tariff: Tax on imported goods.

• Eliminating imports raises domestic prices, benefiting producers but harming consumers.

• Surplus Calculations:

  • Gain to producers: Trapezoid A

  • Loss to consumers: $A + B + C$

  • Deadweight loss: $B + C$

General Case: Tariffs vs. Quotas

• Tariffs generate revenue for the government (rectangle D).

• Quotas transfer rectangle D to foreign producers.

• Net domestic loss: $B + C$ (tariff), $B + C + D$ (quota).

Example: The Sugar Quota

• U.S. restricts sugar imports, raising domestic prices above world prices.

• Consumers pay more; domestic producers benefit; deadweight loss occurs.

9.6 The Impact of a Tax or Subsidy

Specific Taxes

• Specific Tax: A fixed amount per unit sold.

• Tax increases the price paid by buyers and reduces the price received by sellers.

• Surplus Calculations:

  • Buyers lose area A + B

  • Sellers lose area C

  • Government gains area A + D

  • Deadweight loss: area B

Tax Incidence and Elasticity

• The burden of a tax depends on the relative elasticities of supply and demand.

• Pass-through Formula: Percentage of tax passed to consumers: $( rac{ ext{Elasticity of Supply}}{ ext{Elasticity of Supply} + ext{Elasticity of Demand}})$

Subsidies

• Subsidy: Payment to buyers or sellers, effectively lowering the price.

• Benefits are shared between buyers and sellers depending on elasticities.

Example: Tax on Gasoline

• Imposing a $1 tax increases the price at the pump and reduces quantity demanded.

• Deadweight loss is shown by the reduction in consumer and producer surplus.

Summary Table: Effects of Market Interventions

Policy	Consumer Surplus	Producer Surplus	Government Revenue	Deadweight Loss
Price Ceiling	May increase or decrease	Decreases	None	Yes
Price Floor	Decreases	May increase or decrease	None	Yes
Quota	Decreases	Increases	None	Yes
Tariff	Decreases	Increases	Increases	Yes
Subsidy	Increases	Increases	Decreases	Yes

Key Terms and Formulas

• Consumer Surplus: $CS = \int_{0}^{Q^*} [D(Q) - P^*] dQ$

• Producer Surplus: $PS = \int_{0}^{Q^*} [P^* - S(Q)] dQ$

• Deadweight Loss: Area lost due to market intervention, typically triangles between supply and demand curves.

• Elasticity: $E = \frac{\% \text{ change in quantity}}{\% \text{ change in price}}$

Additional info: These notes expand on the brief points in the slides, providing definitions, formulas, and examples for clarity and completeness.