1. Chapter 2 The Basics of Supply and Demand

2. Chapter 2: The Basics of Supply and DemandSlide 2 Changes In Market Equilibrium Equilibrium prices are determined by the relative level of supply and demand. Supply and demand are determined by particular values of supply and demand. Changes in any one or combination of these variables can cause a change in the equilibrium price and/or quantity.

3. Calculating Real Prices: An Example - Eggs & College Consumer Price Index (1983)38.853.882.4107.6130.7 163.0 Nominal Prices Grade A Large Eggs$0.61$0.77$0.84$0.80$0.98$1.04 College Education$2,530$3,403$4,912$8,156$12,800$19,213 Real Prices ($1970) Grade A Large Eggs$0.61$0.56$0.40$0.29$0.30$0.25 College Education$2,530$2,454$2,313$2,941$3,800$4,573 197019751980198519901998

4. Chapter 2: The Basics of Supply and DemandSlide 4 The Price of Eggs and the Price of a College Education Revisited The real price of eggs fell 59% from 1970 to 1998. Supply increased due to the increased mechanization of poultry farming and the reduced cost of production. Demand decreased due to the increasing consumer concern over the health and cholesterol consequences of eating eggs.

5. Chapter 2: The Basics of Supply and DemandSlide 5 Market for Eggs Q (million dozens) P ( 1970 dollars per dozen) D 1970 S 1970 $0.61 5,500 D 1998 S 1998 Prices fell until a new equilibrium was reached at $0.26 and a quantity of 5,300 million dozen $0.26 5,300

6. Chapter 2: The Basics of Supply and DemandSlide 6 The Price of a College Education The real price of a college education rose 68 percent from 1970 to 1995. Supply decreased due to higher costs of equipping and maintaining modern classrooms, laboratories and libraries, and higher faculty salaries. Demand increased due a larger percentage of a larger number of high school graduates attending college.

7. Chapter 2: The Basics of Supply and DemandSlide 7 Market for a College Education Q ( millions of students enrolled)) P ( annual cost in 1970 dollars) D 1970 S 1970 S 1995 D 1995 $4,248 14.9 Prices rose until a new equilibrium was reached at $4,573 and a quantity of 12.3 million students $2,530 8.6

8. Chapter 2: The Basics of Supply and DemandSlide 8 Elasticities of Supply and Demand Generally, elasticity is a measure of the sensitivity of one variable to another. It tells us the percentage change in one variable in response to a one percent change in another variable.

9. Chapter 2: The Basics of Supply and DemandSlide 9 Elasticities of Supply and Demand Measures the sensitivity of quantity demanded to price changes. It measures the percentage change in the quantity demanded for a good or service that results from a one percent change in the price. Price Elasticity of Demand

10. Chapter 2: The Basics of Supply and DemandSlide 10 Elasticities of Supply and Demand The price elasticity of demand is:

11. Chapter 2: The Basics of Supply and DemandSlide 11 Elasticities of Supply and Demand So the price elasticity of demand is also: Price Elasticity of Demand

12. Chapter 2: The Basics of Supply and DemandSlide 12 Elasticities of Supply and Demand Interpreting Price Elasticity of Demand Values 1)Because of the inverse relationship between P and Q; E P is negative. 2)If E P > 1, the percent change in quantity is greater than the percent change in price. We say the demand is price elastic.

13. Chapter 2: The Basics of Supply and DemandSlide 13 Elasticities of Supply and Demand Interpreting Price Elasticity of Demand Values 3)If E P < 1, the percent change in quantity is less than the percent change inprice. We say the demand is price inelastic.

14. Chapter 2: The Basics of Supply and DemandSlide 14 Elasticities of Supply and Demand The primary determinant of price elasticity of demand is the availability of substitutes. Many substitutes demand is price elastic Few substitutes demand is price inelastic Price Elasticity of Demand

15. Chapter 2: The Basics of Supply and DemandSlide 15 Price Elasticities of Demand Q P rice Q = 8 - 2P E p = -1 E p = 0 The lower portion of a downward sloping demand curve is less elastic than the upper portion. 4 8 2 4 Linear Demand Curve Q = a - bP Q = 8 - 2P

16. Chapter 2: The Basics of Supply and DemandSlide 16 Price Elasticities of Demand D P*P* Quantity Price Infinitely Elastic Demand

17. Chapter 2: The Basics of Supply and DemandSlide 17 Price Elasticities of Demand Q*Q* Quantity Price Completely Inelastic Demand

18. Chapter 2: The Basics of Supply and DemandSlide 18 Elasticities of Supply and Demand Income elasticity of demand measures the percentage change in quantity demanded resulting from a one percent change in income. Other Demand Elasticities

19. Chapter 2: The Basics of Supply and DemandSlide 19 Elasticities of Supply and Demand The income elasticity of demand is: Other Demand Elasticities

20. Chapter 2: The Basics of Supply and DemandSlide 20 Elasticities of Supply and Demand Cross elasticity of demand measures the percentage change in the quantity demanded of one good that results from a one percent change in the price of another good. For example consider the substitute goods, rice and wheat. Other Demand Elasticities

21. Chapter 2: The Basics of Supply and DemandSlide 21 Elasticities of Supply and Demand The cross elasticity of demand is: The cross elasticity for substitutes is positive, while that for complements is negative.

22. Chapter 2: The Basics of Supply and DemandSlide 22 Elasticities of Supply and Demand Price elasticity of supply measures the percentage change in quantity supplied resulting from a 1 percent change in price. The elasticity is usually positive because price and quantity supplied are directly related. Elasticities of Supply

23. Chapter 2: The Basics of Supply and DemandSlide 23 Elasticities of Supply and Demand 1981 Supply Curve for Wheat Q S = 1,800 + 240P 1981 Demand Curve for Wheat Q D = 3,550 - 266P The Market for Wheat

24. Elasticities of Supply and Demand Equilibrium: Q S = Q D The Market for Wheat Chapter 2: The Basics of Supply and DemandSlide 24

25. Chapter 2: The Basics of Supply and DemandSlide 25 19811800 + 240P3550 - 266P1800+240P = 3550-266P 506P = 1750 P 1981 = $3.46 19981,944 + 207P3,244 - 283P 1,944+207P = 3,244-283P P 1998 = $2.65 Supply (Q s )Demand (Q D )Equilibrium Price (Q s = Q D ) Changes in the Market: 1981-1998 The Market for Wheat

26. Chapter 2: The Basics of Supply and DemandSlide 26 Short-Run Versus Long-Run Elasticities Price elasticity of demand varies with the amount of time consumers have to respond to a price. Demand

27. Chapter 2: The Basics of Supply and DemandSlide 27 Most goods and services: Short-run elasticity is less than long-run elasticity. (e.g. gasoline, necessities of life) Other Goods (durable): Short-run elasticity is greater than long-run elasticity (e.g. automobiles, machinery) Short-Run Versus Long-Run Elasticities Demand

28. Chapter 2: The Basics of Supply and DemandSlide 28 Gasoline: Short-Run and Long-Run Demand Curves D SR D LR People tend to drive smaller and more fuel efficient cars in the long-run Gasoline Quantity Price

29. Chapter 2: The Basics of Supply and DemandSlide 29 D SR D LR Automobiles Automobiles: Short-Run and Long-Run Demand Curves Quantity Price

30. Chapter 2: The Basics of Supply and DemandSlide 30 Income elasticity also varies with the amount of time consumers have to respond to an income change. Short-Run Versus Long-Run Elasticities Income Elasticities

31. Chapter 2: The Basics of Supply and DemandSlide 31 Most goods and services: Income elasticity is greater in the long-run than in the short run.  Higher incomes may be converted into bigger cars so the income elasticity of demand for gasoline increases with time. Short-Run Versus Long-Run Elasticities Income Elasticities

32. Chapter 2: The Basics of Supply and DemandSlide 32 Other Goods (durables): Income elasticity is less in the long-run than in the short-run. Short-Run Versus Long-Run Elasticities Income Elasticities

33. Chapter 2: The Basics of Supply and DemandSlide 33 Gasoline and automobiles are complementary goods. Short-Run Versus Long-Run Elasticities The Demand for Gasoline and Automobiles The Demand for Gasoline and Automobiles

34. Chapter 2: The Basics of Supply and DemandSlide 34 Gasoline The long-run price and income elasticities are larger than the short-run elasticities. Automobiles The long-run price and income elasticities are smaller than the short-run elasticities. Short-Run Versus Long-Run Elasticities The Demand for Gasoline and Automobiles The Demand for Gasoline and Automobiles

35. Chapter 2: The Basics of Supply and DemandSlide 35 Most goods and services: Long-run price elasticity of supply is greater than short-run price elasticity of supply. Other Goods (durables): Long-run price elasticity of supply is less than short-run price elasticity of supply Short-Run Versus Long-Run Elasticities Supply

36. Chapter 2: The Basics of Supply and DemandSlide 36 S SR Primary Copper: Short-Run and Long-Run Supply Curves Primary Copper: Short-Run and Long-Run Supply Curves Quantity Price Short-Run Versus Long-Run Elasticities S LR Due to limited capacity, firms are limited by output constraints in the short-run. In the long-run, they can expand.

37. Chapter 2: The Basics of Supply and DemandSlide 37 S SR Secondary Copper: Short-Run and Long-Run Supply Curves Secondary Copper: Short-Run and Long-Run Supply Curves Quantity Price Short-Run Versus Long-Run Elasticities S LR Price increases provide an incentive to convert scrap copper into new supply. In the long-run, this stock of scrap copper begins to fall.

38. Chapter 2: The Basics of Supply and DemandSlide 38 First, we must learn how to “fit” linear demand and supply curves to market data. Then we can determine numerically how a change in a variable will cause supply or demand to shift and thereby affect the market price and quantity. Understanding and Predicting the Effects of Changing Market Conditions

39. Chapter 2: The Basics of Supply and DemandSlide 39 Available Data Equilibrium Price, P* Equilibrium Quantity, Q* Price elasticity of supply, E S, and demand, E D. Understanding and Predicting the Effects of Changing Market Conditions

40. Chapter 2: The Basics of Supply and DemandSlide 40 Demand: Q = a - bP a/b Supply: Q = c + dP -c/d P* Q* E D = -bP*/Q* E S = dP*/Q* Understanding and Predicting the Effects of Changing Market Conditions Quantity Price

41. Chapter 2: The Basics of Supply and DemandSlide 41 Let’s begin with the equations for supply and demand: Demand:Q D = a - bP Supply:Q S = c + dP We must choose numbers for a, b, c, and d. Understanding and Predicting the Effects of Changing Market Conditions

42. Chapter 2: The Basics of Supply and DemandSlide 42 Step 1: Recall: Understanding and Predicting the Effects of Changing Market Conditions

43. Chapter 2: The Basics of Supply and DemandSlide 43 For linear demand curves, the change in quantity divided by the change in price is constant (equal to the slope of the curve). Understanding and Predicting the Effects of Changing Market Conditions

44. Chapter 2: The Basics of Supply and DemandSlide 44 Since we will have values for E D, E S, P*, and Q*, we can solve for b & d, and a & c. Understanding and Predicting the Effects of Changing Market Conditions

45. Chapter 2: The Basics of Supply and DemandSlide 45 Deriving the long-run supply and demand for copper: The relevant data are:  Q* = 7.5 mmt/yr.  P* = 75 cents/pound  E S = 1.6  E D = -0.8 Understanding and Predicting the Effects of Changing Market Conditions

46. Chapter 2: The Basics of Supply and DemandSlide 46 E s = d(P*/Q*) 1.6 = d(75/7.5) = 0.1d d = 1.6/0.1 = 16 E d = -b(P*/Q*) -0.8 = -b(.75/7.5) = -0.1b b = 0.8/0.1 = 8 Understanding and Predicting the Effects of Changing Market Conditions

47. Chapter 2: The Basics of Supply and DemandSlide 47 Supply = Q S * = c + dP* 7.5 = c + 16(0.75) 7.5 = c + 12 c = 7.5 - 12 c = -4.5 Q = -4.5 + 16P Demand = Q D * = a -bP* 7.5 = a -(8)(.75) 7.5 = a - 6 a = 7.5 + 6 a =13.5 Q = 13.5 - 8P Understanding and Predicting the Effects of Changing Market Conditions

48. Chapter 2: The Basics of Supply and DemandSlide 48 Setting supply equal to demand gives: Supply = -4.5 + 16p = 13.5 - 8p = Demand 16p + 8p = 13.5 + 4.5 p = 18/24 =.75 Understanding and Predicting the Effects of Changing Market Conditions

49. Chapter 2: The Basics of Supply and DemandSlide 49 Supply: Q S = -4.5 + 16P -c/d Demand: Q D = 13.5 - 8P a/b.75 7.5 Understanding and Predicting the Effects of Changing Market Conditions Mmt/yr Price

50. Chapter 2: The Basics of Supply and DemandSlide 50 supply and demand only depend upon price. Demand could also depend upon income. Demand would then be written as: Understanding and Predicting the Effects of Changing Market Conditions

51. Chapter 2: The Basics of Supply and DemandSlide 51 We know the following information regarding the copper industry: I = 1.0 P* = 0.75 Q* = 7.5 b = 8 Income elasticity: E = 1.3 Understanding and Predicting the Effects of Changing Market Conditions

52. Chapter 2: The Basics of Supply and DemandSlide 52 f can be found by substituting known values into the income elasticity formula: and Understanding and Predicting the Effects of Changing Market Conditions

53. Chapter 2: The Basics of Supply and DemandSlide 53 Solving for f gives: 1.3 = (1.0/7.5)f f = (1.3)(7.5)/1.0 = 9.75 Understanding and Predicting the Effects of Changing Market Conditions

54. Chapter 2: The Basics of Supply and DemandSlide 54 Solving for a gives: 7.5 = a - 8(0.75) + 9.75(1.0) a = 3.75 Understanding and Predicting the Effects of Changing Market Conditions

55. Chapter 2: The Basics of Supply and DemandSlide 55 Declining Demand and the Behavior of Copper Prices The relevant factors leading to a decrease in the demand for copper are: 1) A decrease in the growth rate of power generation 2)The development of substitutes: fiber optics and aluminum

56. Chapter 2: The Basics of Supply and DemandSlide 56 We will try to estimate the impact of a 20 percent decrease in the demand for copper. Recall the equation for the demand curve: Q = 13.5 - 8P Real versus Nominal Prices of Copper 1965 - 1999

57. Chapter 2: The Basics of Supply and DemandSlide 57 Multiply this equation by 0.80 to get the new equation. This gives: Q = (0.80)(13.5 - 8P) Q = 10.8 - 6.4P Recall the equation for supply: Q = -4.5 + 16P Real versus Nominal Prices of Copper 1965 - 1999

58. Chapter 2: The Basics of Supply and DemandSlide 58 The new equilibrium price is: -4.5 + 16P = 10.8 - 6.4P -16P + 6.4P = 10.8 + 4.5 P = 15.3/22.4 P = 68.3 cents/pound Real versus Nominal Prices of Copper 1965 - 1999

59. Chapter 2: The Basics of Supply and DemandSlide 59 The twenty percent decrease in demand resulted in a reduction in the equilibrium price to 68.3 cents from 75 cents. Real versus Nominal Prices of Copper 1965 - 1999

60. Chapter 2: The Basics of Supply and DemandSlide 60 Effects of Government Intervention -- Price Controls If the government decides that the equilibrium price is too high, they may establish a maximum allowable ceiling price.

61. Chapter 2: The Basics of Supply and DemandSlide 61 D Effects of Price Controls Quantity P rice P0P0 Q0Q0 S P max Excess demand If price is regulated to be no higher than P max, quantity supplied falls to Q 1 and quantity demanded increases to Q 2. A shortage results

62. Chapter 2: The Basics of Supply and DemandSlide 62 Summary Supply-demand analysis is a basic tool of microeconomics. The market mechanism is the tendency for supply and demand to equilibrate, so that there is neither excess demand nor excess supply

63. Chapter 2: The Basics of Supply and DemandSlide 63 Summary Elasticities describe the responsiveness of supply and demand to changes in price, income, and other variables.

64. Chapter 2: The Basics of Supply and DemandSlide 64 Summary Simple numerical analysis can often be done by fitting linear supply and demand curves to data on price and quantity and to estimates of elasticities.