1. Chapter 16
Equilibrium

2. Market Equilibrium
A market is in equilibrium when total quantity demanded by buyers equals total quantity supplied by sellers.

3. Market Equilibrium
Market demand p
q=D(p)
D(p)

4. Market Equilibrium
Market supply p
q=S(p)
S(p)

5. Market Equilibrium Market demand Market supply p q=S(p) q=D(p)
D(p), S(p)

6. Market Equilibrium Market demand Market supply p q=S(p) p* q=D(p) q*
D(p), S(p)

7. Market Equilibrium Market demand Market supply p q=S(p)
D(p*) = S(p*); the market is in equilibrium. p*
q=D(p) q*
D(p), S(p)

8. Market Equilibrium Market demand Market supply p q=S(p)
D(p’) < S(p’); an excess of quantity supplied over quantity demanded. p’ p*
q=D(p)
D(p’)
S(p’)
D(p), S(p)

9. Market Equilibrium Market price must fall towards p*. Market demand
Market supply p
q=S(p)
D(p’) < S(p’); an excess of quantity supplied over quantity demanded. p’ p*
q=D(p)
D(p’)
S(p’)
D(p), S(p)
Market price must fall towards p*.

10. Market Equilibrium Market demand Market supply p q=S(p)
D(p”) > S(p”); an excess of quantity demanded over quantity supplied. p* p”
q=D(p)
S(p”)
D(p”)
D(p), S(p)

11. Market Equilibrium Market price must rise towards p*. Market demand
Market supply p
q=S(p)
D(p”) > S(p”); an excess of quantity demanded over quantity supplied. p* p”
q=D(p)
S(p”)
D(p”)
D(p), S(p)
Market price must rise towards p*.

12. Market Equilibrium
An example of calculating a market equilibrium when the market demand and supply curves are linear.

13. Market Equilibrium Market demand Market supply p S(p) = c+dp p*
D(p) = a-bp q*
D(p), S(p)

14. Market Equilibrium What are the values of p* and q*? Market demand
Market supply p
S(p) = c+dp
What are the values of p* and q*? p*
D(p) = a-bp q*
D(p), S(p)

15. Market Equilibrium
At the equilibrium price p*, D(p*) = S(p*).

16. Market Equilibrium
At the equilibrium price p*, D(p*) = S(p*). That is,

17. Market Equilibrium
At the equilibrium price p*, D(p*) = S(p*). That is,
which gives

18. Market Equilibrium
At the equilibrium price p*, D(p*) = S(p*). That is,
which gives
and

19. Market Equilibrium Market demand Market supply p S(p) = c+dp
D(p) = a-bp
D(p), S(p)

20. Quantity Taxes
What is the effect of a quantity tax on a market’s equilibrium?
How are prices affected?
How is the quantity traded affected?
Who pays the tax?
How are gains-to-trade altered?

21. Quantity Taxes
A tax rate t makes the price paid by buyers, pb, higher by t from the price received by sellers, ps.

22. Quantity Taxes Even with a tax the market must clear.
I.e. quantity demanded by buyers at price pb must equal quantity supplied by sellers at price ps.

23. Quantity Taxes
and
describe the market’s equilibrium.

24. Quantity Taxes
and
describe the market’s equilibrium. Notice that these two conditions apply no matter if the tax is levied on sellers or on buyers.

25. Quantity Taxes & Market Equilibrium
Who pays the tax of $t per unit traded?
The division of the $t between buyers and sellers is the incidence of the tax.

26. Quantity Taxes & Market Equilibrium
Market demand
Market supply p pb pb pb p* ps qt q*
D(p), S(p)

27. Quantity Taxes & Market Equilibrium
Market demand
Market supply p
Tax paid by buyers pb pb pb p* ps qt q*
D(p), S(p)

28. Quantity Taxes & Market Equilibrium
Market demand
Market supply p pb pb pb p*
Tax paid by sellers ps qt q*
D(p), S(p)

29. Quantity Taxes & Market Equilibrium
Market demand
Market supply p
Tax paid by buyers pb pb pb p*
Tax paid by sellers ps qt q*
D(p), S(p)

30. Tax Incidence and Own-Price Elasticities
The incidence of a quantity tax depends upon the own-price elasticities of demand and supply.

31. Tax Incidence and Own-Price Elasticities
Around p = p* the own-price elasticity of demand is approximately

32. Tax Incidence and Own-Price Elasticities
Around p = p* the own-price elasticity of demand is approximately

33. Tax Incidence and Own-Price Elasticities
Around p = p* the own-price elasticity of supply is approximately

34. Tax Incidence and Own-Price Elasticities
Around p = p* the own-price elasticity of supply is approximately

35. Tax Incidence and Own-Price Elasticities
Market demand
Market supply p
Tax paid by buyers pb pb pb p*
Tax paid by sellers ps qt q*
D(p), S(p)

36. Tax Incidence and Own-Price Elasticities
Market demand
Market supply p
Tax paid by buyers pb pb pb p*
Tax paid by sellers ps qt q*
D(p), S(p)
Tax incidence =

37. Tax Incidence and Own-Price Elasticities

38. Tax Incidence and Own-Price ElasticitiesSo

39. Tax Incidence and Own-Price Elasticities
Tax incidence is
Nominator of LHS: part of tax passed
along the consumer.
Denominator of RHS: part of tax passed
along the producer.

40. Tax Incidence and Own-Price Elasticities
Tax incidence is
Part of tax passed along the consumer is
the smaller the more elastic D and the more
inelastic S.
Part of tax passed along the producer is
the smaller the more elastic S and the more
inelastic D.

41. Deadweight Loss and Own-Price Elasticities
A quantity tax imposed on a competitive market reduces the quantity traded and so reduces gains-to-trade (i.e. the sum of Consumers’ and Producers’ Surpluses).
The lost total surplus is the tax’s deadweight loss, or excess burden.

42. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p
No tax p* q*
D(p), S(p)

43. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p
No tax CS p* q*
D(p), S(p)

44. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p
No tax p* PS q*
D(p), S(p)

45. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p
No tax CS p* PS q*
D(p), S(p)

46. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p
No tax CS p* PS q*
D(p), S(p)

47. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p
The tax reduces both CS and PS pb CS $t p* ps PS qt q*
D(p), S(p)

48. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p
The tax reduces both CS and PS, transfers surplus to government pb CS $t p*
Tax ps PS qt q*
D(p), S(p)

49. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p
The tax reduces both CS and PS, transfers surplus to government pb CS $t p*
Tax ps PS qt q*
D(p), S(p)

50. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p
The tax reduces both CS and PS, transfers surplus to government pb CS $t p*
Tax ps PS qt q*
D(p), S(p)

51. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p
The tax reduces both CS and PS, transfers surplus to government, and lowers total surplus. pb CS $t p*
Tax ps PS qt q*
D(p), S(p)

52. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p pb CS $t p*
Tax ps PS
Deadweight loss qt q*
D(p), S(p)

53. Deadweight Loss and Own-Price Elasticities
Market demand
Market supply p pb $t p* ps
Deadweight loss qt q*
D(p), S(p)