1. Consumer and Producer Surplus
CHAPTER 6
Consumer and Producer Surplus

2. Consumer Surplus and the Demand Curve
Let’s start with some basic concepts…
A consumer’s willingness to pay for a good is really their maximum price.
Individual consumer surplus is the difference between actual price, and what you would have been willing to pay.
(You bought it for less= consumer surplus!!!)

3. The Demand Curve for Used Textbooks
A consumer’s willingness to pay for a good is the maximum price at which he or she would buy that good.

5. Willingness to Pay and Consumer Surplus
Total consumer surplus is the sum of the individual consumer surpluses of all the buyers of a good.
The term consumer surplus is often used to refer to both individual and to total consumer surplus.

6. Consumer Surplus
The total consumer surplus generated by purchases of a good at a given price is equal to the area below the demand curve but above that price.

7. How Changing Prices Affect Consumer Surplus
A fall in the price of a good increases consumer surplus through two channels:
A gain to consumers who would have bought at the original price and
A gain to consumers who are persuaded to buy by the lower price.
Let’s see these two channels in the following graph…

8. A Fall in the Price of Used Textbooks…

9. A Fall in the Market Price Increases Consumer Surplus

10. Producer Surplus and the Supply Curve
A potential seller’s cost is the lowest price at which he or she is willing to sell a good. Cost includes profit for the producer.
Individual producer surplus is the net gain to a seller from selling a good. It is equal to the difference between the price received and the seller’s cost. (If producers sell it for more than cost, that generates producer surplus!!!)
Total producer surplus = the sum of the individual producer surpluses.

11. The Supply Curve for Used Textbooks

12. Producer Surplus in the Used-Textbook Market

13. Producer Surplus
The total producer surplus from sales of a good at a given price is the area above the supply curve but below that price.

14. Changes in Producer Surplus
When the price of a good rises, producer surplus increases through two channels:
The gains of those who would have supplied the good even at the original, lower price and
The gains of those who are induced to supply the good by the higher price.

15. A Rise in the Price Increases Producer Surplus

16. Putting it together: Total Surplus
The total surplus = producer surplus + consumer surplus.
There can be both consumer and producer surplus in the same transaction.
(Example: Pretty Woman)

17. Total Surplus

18. Consumer Surplus, Producer Surplus, and the Gains from Trade
The previous graph shows that both consumers and producers are better off because there is a market in this good, i.e. there are gains from trade.
These gains from trade are the reason everyone is better off participating in a market economy than they would be if each individual tried to be self-sufficient.

19. The Efficiency of Markets: A Preliminary View
The maximum possible total surplus is achieved at market equilibrium.
Consider three ways in which you might try to increase the total surplus…

20. Reallocating Consumption among Consumers

21. Reallocating Sales among sellers

22. Changing the Quantity Lowers Total Surplus

23. Important!
Although the market equilibrium maximizes the total surplus, this does not mean that it is the best outcome for every individual consumer and producer.
For instance, a price floor that kept the price up would benefit some sellers.
But in the market equilibrium there is no way to make some people better off without making others worse off—and that’s the definition of efficiency.

24. Market Failures
Under certain conditions, market failure occurs and the market produces an inefficient outcome.
The three principal sources are
attempts to capture more resources that produce inefficiencies (monopolies)
side effects from certain transactions
(externalities) (fireworks) (cigarettes)
problems in the nature of the goods themselves
(used cars) or (Lake Michigan fish)

25. Applying Consumer and Producer Surplus: The Efficiency Costs of a Tax
A tax causes a deadweight loss to society, because less of the good is produced and consumed than in the absence of the tax. As a result, some mutually beneficial trades between producers and consumers do not take place.

26. A Tax Reduces Consumer and Producer Surplus

27. The Deadweight Loss of a Tax

28. Deadweight Loss and Elasticities
Ceteris paribus, how can we predict the size of the deadweight loss associated with a given policy?

29. In panel (a), the deadweight-loss triangle is large because demand is relatively elastic—a large number of transactions fail to occur because of the tax.
In panel (b), the same supply curve is drawn as in panel (a), but demand is now relatively inelastic; as a result, the triangle is small because only a small number of transactions are forgone.

30. In panel (c), an elastic supply curve gives rise to a large deadweight-loss triangle, but in panel (d) an inelastic supply curve gives rise to a small deadweight-loss triangle.
If you want to lessen the efficiency costs of taxation, you should devise taxes to fall on goods for which either demand or supply, or both, is relatively inelastic.
Using a tax to purposely decrease the amount of a harmful activity, such as underage drinking, will have the most impact when that activity is elastically demanded or supplied.

31. The End of Chapter 6