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, ensuring efficient allocation of resources.

• 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.

• 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 supply or demand. These shifts are caused by factors other than price, leading to a new equilibrium price and quantity.

• Factors Shifting Demand:

  • Changes in income

  • Prices of substitutes or complements

  • Consumer tastes and preferences

• Factors Shifting Supply:

  • Changes in technology

  • Input prices

• Distinguishing Movements vs. Shifts:

  • Price change causes movement along the curve (change in Qd/Qs)

  • Non-price change causes shift of the curve (change in D/S)

  • 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 (health food trend) and increased supply (factory production) by 2003. The model predicts higher equilibrium quantity and potentially lower or higher price depending on the relative shifts.

Taxes

Government intervention through taxes affects market equilibrium, creating deadweight loss and altering the distribution of tax burden between consumers and producers.

• Per Unit Tax on Producers:

  • Tax rate: per unit

  • Increases marginal cost for each firm

  • Shifts supply curve upward (leftward)

  • Does not shift demand curve

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

• Tax Incidence: Refers to how the burden of tax is shared between consumers and producers.

  • Lower price elasticity of demand → consumers pay more of the tax

  • Lower price elasticity of supply → producers pay more of the tax

  • Tax share formula: where is elasticity of supply and is elasticity of demand

• Per Unit Tax on Consumers:

  • Tax rate: per unit

  • Shifts demand curve downward (leftward)

  • Supply curve remains unchanged

  • Producers perceive lower demand

• 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 not 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 targeted.

Quota – Quantity Control

Quotas are government-imposed limits on the quantity of a good that can be produced or sold. They are commonly used in agriculture to control supply and stabilize prices.

• Definition: A quota is a license for a producer to produce a specified amount of a crop or animal product.

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

• Effects of Quotas:

  1. Decrease in quantity produced

  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)

Summary Table: Effects of Government Intervention

Additional info: Deadweight loss refers to the reduction in total surplus (consumer plus producer surplus) that occurs when market equilibrium is distorted by taxes, subsidies, or quotas. Elasticity measures the responsiveness of quantity demanded or supplied to changes in price, and is crucial in determining tax incidence and the effects of government intervention.