Chapter 4: Economic Efficiency, Government Price Setting, and Taxes

Chapter Outline

• Consumer Surplus and Producer Surplus

• The Efficiency of Competitive Markets

• Government Intervention in the Market: Price Floors and Price Ceilings

• The Economic Effect of Taxes

• Appendix: Quantitative Demand and Supply Analysis

Consumer Surplus and Producer Surplus

Definitions and Concepts

Consumer surplus and producer surplus are key measures of the benefits that participants receive from market transactions.

• Surplus (noun): Something that remains above what is used or needed.

• Consumer Surplus: The difference between the highest price a consumer is willing to pay for a good or service and the actual price the consumer pays.

• Producer Surplus: The difference between the lowest price a firm would be willing to accept for a good or service and the price it actually receives.

Example: Deriving the Demand Curve for Chai Tea

Suppose four people (Theresa, Tom, Terri, Tim) are each interested in buying a cup of chai tea. Each has a maximum price they are willing to pay:

If the price is above $6, no tea will be sold. At $6, one cup will be sold, and so on.

Marginal Benefit and Consumer Surplus

• Marginal Benefit: The additional benefit to a consumer from consuming one more unit of a good or service.

• Consumer surplus is the area below the demand curve and above the market price, up to the quantity purchased.

• As price falls, consumer surplus increases because more consumers benefit.

Measuring Consumer Surplus

For example, if the price of chai tea is $3.50 per cup:

• Theresa (willing to pay $6.00) gets a surplus of $6.00 - $3.50 = $2.50.

• Tom (willing to pay $5.00) gets a surplus of $5.00 - $3.50 = $1.50.

• Terri (willing to pay $4.00) gets a surplus of $4.00 - $3.50 = $0.50.

• Tim (willing to pay $3.00) is indifferent at $3.50 and does not buy.

The total consumer surplus is the sum of individual surpluses, represented graphically as the area between the demand curve and the price line.

Producer Surplus

• Producer surplus is the difference between the price a producer receives and the marginal cost of production for each unit sold.

• Marginal Cost: The change in a firm's total cost from producing one more unit of a good or service.

• Producer surplus is the area above the supply curve and below the market price, up to the quantity sold.

What Do Consumer Surplus and Producer Surplus Measure?

• Consumer surplus measures the net benefit to consumers from participating in a market.

• Producer surplus measures the net benefit to producers from participating in a market.

• Both are measured in monetary terms and represent the difference between what participants are willing to pay/accept and what they actually pay/receive.

The Efficiency of Competitive Markets

Economic Efficiency

A market is considered efficient if:

• All trades take place where the marginal benefit to consumers exceeds the marginal cost to producers.

• No further trades can increase total surplus (the sum of consumer and producer surplus).

• Economic surplus is maximized at the competitive equilibrium.

Marginal Benefit Equals Marginal Cost

• At the competitive equilibrium, the marginal benefit to consumers of the last unit produced equals the marginal cost of production.

• If quantity is too low, the value to consumers of the next unit exceeds the cost to producers (inefficiency).

• If quantity is too high, the cost to producers of the last unit exceeds the value to consumers (inefficiency).

Deadweight Loss

• Deadweight loss is the reduction in economic surplus resulting from a market not being in competitive equilibrium.

• It represents the loss of efficiency in a market.

• At equilibrium, deadweight loss is zero.

Government Intervention in the Market: Price Floors and Price Ceilings

Definitions

• Price Ceiling: A legally determined maximum price that sellers may charge.

• Price Floor: A legally determined minimum price that sellers may receive.

• Examples: Minimum wages (price floor), rent controls (price ceiling), agricultural price supports.

Economic Effects of Price Floors

• Price floors set above equilibrium price create surpluses (excess supply).

• Example: If the equilibrium price of wheat is $6.50/bushel and a price floor is set at $8.00, quantity supplied exceeds quantity demanded, resulting in surplus wheat.

• Economic surplus is reduced by the deadweight loss created.

Economic Effects of Price Ceilings

• Price ceilings set below equilibrium price create shortages (excess demand).

• Example: Rent control may lower the price of apartments but results in fewer apartments being rented and a shortage.

• Consumer surplus may increase for some, but overall economic surplus falls due to deadweight loss.

Illegal Markets and Peer-to-Peer Sites

• Shortages may lead to illegal markets where goods are sold at prices violating government regulations.

• Peer-to-peer rental sites (e.g., Airbnb) may help alleviate shortages but can reduce legal protections for buyers and sellers.

Winners and Losers from Price Controls

• Some people win (e.g., renters who get lower rents), others lose (e.g., those unable to find apartments).

• There is a loss of economic efficiency (deadweight loss).

The Economic Effect of Taxes

Per-Unit Taxes

• Governments often impose per-unit taxes (a fixed dollar amount per unit sold).

• Example: Federal excise tax on gasoline.

• Taxes shift the supply curve upward by the amount of the tax, increasing the price paid by consumers and reducing the price received by producers.

Tax Incidence

• Tax Incidence: The actual division of the burden of a tax between buyers and sellers in a market.

• Incidence depends on the relative elasticities of demand and supply, not on who is legally required to pay the tax.

• If demand is inelastic, consumers bear more of the tax burden; if supply is inelastic, producers bear more.

Deadweight Loss from Taxes

• Taxes create deadweight loss by reducing the quantity traded below the efficient level.

• A tax is more efficient if it raises the same revenue with a smaller deadweight loss.

Appendix: Quantitative Demand and Supply Analysis

Solving for Equilibrium

• Suppose demand and supply for apartments are given by:

• Demand:

• Supply:

• Set to find equilibrium:

• Equilibrium quantity:

Consumer and Producer Surplus Calculation

• Consumer surplus: Area below demand curve and above price.

• Producer surplus: Area above supply curve and below price.

• Use the area of a triangle:

Effect of Rent Controls

• Imposing a rent ceiling below equilibrium reduces quantity supplied and creates deadweight loss.

• Consumer surplus may increase for some, but total surplus falls.

Summary Table: Effects of Rent Controls (Values in Millions)

Key Takeaway: Government interventions such as price floors, price ceilings, and taxes can create inefficiencies in markets, leading to deadweight loss and redistributing surplus among market participants.