Market Equilibrium and Government Intervention

Market Equilibrium

Market equilibrium is a fundamental concept in microeconomics, describing the point at which the quantity demanded equals the quantity supplied. This intersection determines the market price and quantity traded.

• Motivation (Assumption): Maximization - Economic agents (consumers and producers) are assumed to maximize their respective objectives: utility for consumers and profit for producers.

• Behaviour (Decision Making): Marginal Analysis

  • Consumers: Choose quantity (Q) to maximize utility or consumer surplus. The condition for optimal choice is , where MV(Q) is marginal value and P is price.

  • Producers: Choose quantity (Q) to maximize profit or producer surplus. The condition for optimal choice is , where MC(Q) is marginal cost.

• Demand and Supply Curves: Represent individual and market behaviors.

• Equilibrium:

  • Market Demand = Market Supply

  • Gains from trade (Consumer Surplus + Producer Surplus) are maximized.

  • Competitive equilibrium is efficient.

• Adam Smith's Principle: Individual self-interest leads to maximized societal wealth ("private vice leads to public virtue").

Change in Equilibrium: Shifts in Supply and Demand

Market equilibrium can change due to shifts in demand or supply, resulting in new prices and quantities.

• Factors Shifting Demand:

  • Changes in income

  • Prices of substitutes or complements

  • Tastes and preferences

• Factors Shifting Supply:

  • Changes in technology

  • Input prices

• Result: Shifts in demand and/or supply curves lead to a new intersection, creating a new equilibrium price and quantity.

• Distinction:

  • Change in quantity demanded/supplied (/) ≠ Change in demand/supply (/)

  • Price change → movement along the curve (change in /)

  • Non-price change → shift of the curve (change in /)

  • Increase in demand/supply → rightward shift

  • Decrease in demand/supply → leftward shift

• Example: The tofu market in Canada shifted from limited supply and demand in 1977 to increased demand and factory-based supply in 2003, resulting in higher equilibrium quantity and potentially lower price due to technological advances.

Taxes

Government intervention through taxes affects market equilibrium, creating deadweight loss and altering the distribution of tax burden (tax incidence).

• Per Unit Tax on Producers:

  • Tax rate: per unit

  • Increases marginal cost () for each firm

  • Shifts supply curve upward (leftward)

  • Does not directly affect demand curve

  • Creates deadweight loss (DWL) by reducing output and unrealized gains from trade

• Tax Incidence: The division of tax burden between consumers and producers depends on the price elasticities of demand and supply.

  • Lower price elasticity of demand → consumers pay a larger fraction of tax

  • Lower price elasticity of supply → producers pay a larger fraction of tax

  • Tax share of consumers:

• Per Unit Tax on Consumers:

  • Tax rate: per unit

  • Shifts demand curve downward (leftward)

  • Supply curve remains unchanged

  • Producers perceive lower demand at each price

• Key Questions:

  • Should government tax producers or consumers?

  • To maximize tax revenue, should government tax goods with inelastic or elastic demand?

  • Is grocery demand inelastic or elastic? Why is grocery rarely taxed?

  • To minimize deadweight loss, should government tax goods with inelastic or elastic demand?

• Per Unit Subsidy: A negative tax, which increases output and can also create deadweight loss if not efficiently allocated.

Quota – Quantity Control

Quotas are government-imposed limits on the quantity of a good that can be produced or sold, commonly used in agriculture.

• Definition: A quota is a license for a producer to supply a specified amount of a product.

• Examples: Canada's supply management system for dairy and poultry products.

• Effects of Quotas:

  1. Decrease in quantity supplied

  2. Increase in price

  3. Wealth transfer from consumers to producers

  4. Deadweight loss (DWL) due to reduced gains from trade

• Key Questions:

  • How much would a quota (license) sell for?

  • Can all farmers benefit from the quota system? (Transitional gains trap)

Additional info:

• Deadweight Loss (DWL): Refers to the loss of economic efficiency when equilibrium for a good or service is not achieved or is not achievable.

• Transitional Gains Trap: Occurs when the initial recipients of quotas benefit, but over time, the value of quotas is capitalized into asset prices, and new entrants do not benefit.