1. Supply,Demand, and the Market Process
Chapter 3
Supply,Demand, and the Market Process

2. 1. Consumer Choice and the Law of Demand

3. Law of Demand
Law of Demand: There is an inverse relationship between the price of a good and the quantity consumers are willing to purchase.
As price of a good rises, consumers buy less.
The availability of substitutes --goods that do similar functions -- explains this negative relationship.

4. Market Demand Schedule
A market demand schedule is a table that shows the quantity of a good people will demand at varying prices.
Consider the market for cellular phones. A market demand schedule lays out the amount of cell phones that are demanded in the market for a spectrum of prices.
We can graph these points (price and the respective demand) to make a demand curve for cell phones.

5. Market Demand Schedule
Price (monthly bill)
140
Cell Phone Price (monthly bill)
Millions of Cell Phone Subscribers
Demand
120 $
100 $ $ 80 $ $ 60 $ $ 5 10 15 20 25 30
Quantity (of Cell Phone Subscribers)

6. Market Demand Schedule
Price (monthly bill)
140
Demand
120
Notice how the law of demand is reflected by the shape of the demand curve.
100
As the price of a good rises … 80
. . . consumers buy less. 60 5 10 15 20 25 30
Quantity (of Cell Phone Subscribers)

7. Market Demand Schedule
Price (monthly bill)
140
Demand
120
The height of the demand curve at any quantity shows the maximum price that consumers are willing to pay for that additional unit.
100
Here, for the 11th unit . . . 80
. . . consumers are only willing to pay up to $73 for it. 60
While they would be willing to pay up to $92 for the (millionth) unit. 5 10 15 20 25 30
Quantity (of Cell Phone Subscribers)

8. Consumer Surplus
Consumer Surplus - the area below the demand curve but above the actual price paid.
Consumer surplus is the difference between the amount consumers are willing to pay and the amount they have to pay for a good.
Lower market prices will increase consumer surplus.

9. Quantity (of Cell Phone Subscribers)
Consumer Surplus
Lets consider the market for cellular phones again. This time we will assume that the demand for cell phones is more linear and that the market price is $100.
Price (monthly bill)
Demand
140
120
If the market price is $100, then the 25th unit will not sell because those who demand it are only willing to pay $60 for cellular phone service.
Market Price = $100
100 80
At $100, the 15th unit will sell because those who demand it are willing to pay up to $100 for cellular phone service. 60
At $100, the 10th unit will sell because those who demand it are willing to pay up to $120 for cellular phone service. 5 10 15 20 25 30
Quantity (of Cell Phone Subscribers)

10. Quantity (of Cell Phone Subscribers)
Consumer Surplus
Price (monthly bill)
Demand
For all those goods under units, people are willing to pay more than $100 for service.
140
120
The area, represented by the distance above the actual price paid and below the demand curve, is called consumer surplus.
Market Price = $100
100 80
This area represents the net gains to buyers from market exchange. 60 5 10 15 20 25 30
Quantity (of Cell Phone Subscribers)

11. Elastic and Inelastic Demand Curves
Elastic demand - quantity demanded is sensitive to small price changes.
Easy to substitute away from good.
Inelastic demand - quantity demanded is not sensitive to price changes.
Difficult to substitute away from good.

12. Elastic and Inelastic Demand Curves
If the market price for gasoline was to rise from $1.25 to $2.00, the quantity demanded in the market decreases insignificantly (from 8 to 7 units).
2.00
Gasoline
1.25
If the market price for tacos rises from $1.25 to $2.00, the quantity demanded in the market decreases significantly (from 8 to 1 unit). 1 2 3 4 5 6 7 8 9 10
2.00
Tacos
Taco demand is highly sensitive to price changes and can be described as elastic; gasoline demand is relatively insensitive to price changes and can be described as inelastic.
1.25 1 2 3 4 5 6 7 8 9 10

13. 2. Changes in Demand Versus Changes in Quantity Demanded

14. Changes in Demand and Quantity Demanded
Change in Demand - shift in entire demand curve.
Change in Quantity Demanded - movement along the same demand curve in response to a price change.

15. Quantity (of Compact Disks per yr)
Change in Demand
Price (dollars)
If CDs cost $15 each, the CD demand curve D1 shows that units would be demanded. 25 D2 20
If the price of CDs changed to $7.50, the quantity demanded for CDs would increase to 20 units. 15
If, somehow, the preferences for CDs changed then the demand for CDs may change. 10 5
Here we will assume that consumer income increases, increasing demand for CDs at all price levels. At $ units are now demanded. D1 5 10 10 15 15 20 20 25 30
Quantity (of Compact Disks per yr)

16. Demand Curve Shifters Changes in Consumer Income
Change in the Number of Consumers
Change in Price of Related Good
Changes in Expectations
Demographic Changes
Changes in Consumer Tastes and Preferences

17. Questions for Thought:
1. Which of the following do you think would lead to an increase in the current demand for beef: (a) higher pork prices, (b) higher incomes, (c) higher prices of feed grains used to feed cows, (d) good weather conditions leading to a bumper (very good) corn crop, (e) an increase in the price of beef?
2. What is being held constant when a demand curve for a specific product (like shoes or apples, for example) is constructed? Explain why the demand curve for a product slopes downward and to the right.

18. 3. Producer Choice and the Law of Supply

19. Producers
Opportunity Cost of Production - the sum of the producer’s cost of employing each resource required to produce the good.
Firms will not stay in business for long unless they are able to cover the cost of all resources employed, including the opportunity cost of those owned by the firm.

20. Role of Profits and Losses
Profit occurs when revenues are greater than cost.
Firms supplying goods for which consumers are willing to pay more than the opportunity cost of resources used will make a profit.
Firms making a profit will expand and those with a loss will contract.

21. Law of Supply
Law of Supply - there is a positive relationship between the price of a product and the amount of it that will be supplied.
As the price of a product rises, producers will be willing to supply more.

22. Market Supply Schedule
Price (monthly bill)
Supply
140
Cell Phone Price (monthly bill)
Quantity of Cell Phones Supplied
120 $
100 $ $ 80 $ $ 60 $ $ 5 10 15 20 25 30
Quantity (of Cell Phone Subscribers)

23. Market Supply Schedule
Price (monthly bill)
Supply
140
120
Notice how the law of supply is reflected by the shape of the supply curve.
100
As the price of a good rises … 80
. . . producers supply more. 60 5 10 15 20 25 30
Quantity (of Cell Phone Subscribers)

24. Market Supply Schedule
Price (monthly bill)
Supply
The height of the supply curve at any quantity shows the minimum price necessary to induce producers to supply that next unit to market.
140
120
100
Here, for the 11th unit . . .
. . . producers require $73 to induce them to supply it. 80
The height of the supply curve at any quantity also shows the opportunity cost of producing that next unit of the good. 60 5 10 15 20 25 30
Quantity (of Cell Phone Subscribers)

25. Quantity (of Cell Phone Subscribers)
Producer Surplus
Lets consider the market for cellular phones again. This time we will assume that the supply for cell phones is more linear and that the market price is $100.
Price (monthly bill)
Supply
140
120
If the market price is $100, then the 25th unit will not be produced because the cost of supplying it exceeds the market price of $140.
Market Price = $100
100 80
At $100, the 15th unit will be produced because those who supply it are willing to do so for for at least $100. 60
At $100, the 10th unit will be produced because those who supply it are willing to do so for at least $80. 5 10 15 20 25 30
Quantity (of Cell Phone Subscribers)

26. Quantity (of Cell Phone Subscribers)
Producer Surplus
Price (monthly bill)
Supply
For market outputs of less then units, producers are willing to supply the good for $100.
140
120
The area represented by the distance above the supply curve but below the actual sales price is called producer surplus.
Market Price = $100
100
This area is the difference between the minimum amount required to induce producers to supply a good and the amount they actually receive. 80 60 5 10 15 20 25 30
Quantity (of Cell Phone Subscribers)

27. Elastic and Inelastic Supply Curves
Elastic supply- quantity supplied is sensitive to small price changes.
Inelastic supply - quantity supplied is not sensitive to price changes.

28. Elastic and Inelastic Supply Curves
If the market price for motor oil was to rise from $1.25 to $2.00, the quantity supplied in the market increases insignificantly (from 7 to 8 units).
2.00
1.25
If the market price for burgers rises from $ to $2.00, the quantity supplied in the market increases substantially (from 1 to 8 units). 1 2 3 4 5 6 7 8 10 9
2.00
Burger supply is highly sensitive to price changes and can be described as elastic; motor oil supply is relatively insensitive to price changes and can be described as inelastic.
1.25 1 2 3 4 5 6 7 8 9 10

29. Short Run and Long Run
Short Run - Firms don’t have enough time to change plant size.
Supply tends to be inelastic in the short run.
Long Run - Firms have enough time to change plant size.
Supply tends to be much more elastic in the long run.

30. 4. Changes in Supply Versus Changes in Quantity Supplied

31. Changes in Supply and Quantity Supplied
Change in Supply - shift in entire supply curve.
Change in Quantity Supplied - movement along the same supply curve in response to a price change.

32. Change in Supply The Market for Gasoline
Price (dollars) S2
If the market price for gas is $1.50 a gallon, the gasoline supply curve S1 shows that units would be supplied.
2.50
The Market for Gasoline S1
2.00
If the market price of gas changed to $.75, the quantity supplied of gasoline would decrease to 10 units.
1.50
If, somehow, the opportunity costs for gas manufacturers changed then the supply of gas may change.
1.00
.50
Here we will assume that the cost of crude oil (an input in gasoline) increases, decreasing the supply of gas at all price levels. Now at $1.50, 15 units of gasoline are supplied. 5 10 10 15 15 20 20 25 30
Quantity (Millions of Gal of Gas)

33. Supply Curve Shifters Changes in Resource Prices Change in Technology
Elements of Nature and Political Disruptions
Changes in Taxes

34. Questions for Thought:
What must a firm do in order to make profit?
1. What are profits and losses?
2. Define consumer and producer surplus. What is meant by economic efficiency and how does it relate to consumer and producer surplus?

35. 5. How Market Prices are Determined

36. Market Equilibrium >
This table and graph indicate the demand and supply conditions for oversized playing cards.
Demand
Supply
Equilibrium will occur where the quantity demanded equals the quantity supplied. If the price in the market exceeds the equilibrium level, market forces will guide it to equilibrium. 13 12 11 10 9
A price of $12 in this market will result in . . . 8
resulting in excess supply.
quantity demanded of 450 and
quantity
supplied of 7
With an excess supply present, there will be downward pressure on price to clear the market.
350
400
400
450
500
550
600
650
>
Excess Supply
Quantity Supplied = 600
Downward
Quantity Demanded = 450

37. Market Equilibrium > < Demand Supply13
A price of $8 in this market will result in . . . 12
quantity supplied of 500 and
resulting in excess demand.
quantity
demanded of 11 10
With an excess demand present, there will be upward pressure on price to clear the market. 9 8 7
350
400
400
450
500
550
600
650
>
Excess Supply
Quantity Supplied = 500
Downward
Quantity Demanded = 650
<
Excess Demand
Upward

38. Market Equilibrium > = < Demand
Supply 13
A price of $10 in this market will result in . . . 12
quantity
demanded of
resulting in a balance.
quantity supplied of 550 and 11 10
With a balance present, there will be an equilibrium and the market will clear. 9 8 7
350
400
400
450
500
550
600
650
>
Excess Supply
Quantity Supplied = 550
Downward =
Balance
Equilibrium
<
Quantity Demanded = 550
Excess Demand
Upward

39. Market Equilibrium > = < excess supply excess demand Demand
At every price above market equilibrium there is excess supply and there will be downward pressure on the price level. 13 12 11
Equilibrium Price
At every price below market equilibrium there is excess demand and there will be upward pressure on the price level. 10
excess demand 9 8 7
It is at equilibrium that prices will rest.
350
400
400
450
500
550
600
650
>
Excess Supply
Downward =
Balance
Equilibrium
<
Excess Demand
Upward

40. Net Gains to Buyers and Sellers
Returning to the market for cell phones, if the market price is driven to equilibrium through market pressures to exist where supply equals demand, then the market equilibrium in the cell phone market should be driven to $100 per month.
Price (monthly bill)
Supply
Demand
140
120
Market Equilibrium Price = $100
If the area above the market price and below the demand curve is called consumer surplus . . .
100
. . . and the area above the supply curve but below the market price is called producer surplus . . . 80 60
. . . Then the combined area represented in the graph to the right represents the net gains to buyers and sellers. It is here that all potential gains from production and exchange are realized. 5 10 15 20 25 30
Quantity (of Cell Phone Subscribers)

41. 6. How Markets Respond to Changes in Supply and Demand

42. Effects of a Change in Demand
If Demand decreases, the equilibrium price and quantity will fall.
If Demand increases, the equilibrium price and quantity will rise.

43. Market Adjustment to an Increase in Demand
Consider the market for eggs.
Price ($ per doz)
Prior to Easter season, the market for eggs produces an equilibrium where Supply equals Demand1 at a market price of $ .80 and output of Q1.
Demand2
Supply
1.40
1.20
Demand1
When the Easter season arrives, the demand by consumers for eggs increases from Demand1 to Demand2. What happens to the equilibrium price and output level?
1.00 `
.80
At $ .80 a dozen the quantity demanded exceeds the quantity supplied. There is upward pressure on price inducing the existing suppliers to increase their quantity supplied to Q2, pushing the equilibrium price up to $1.00.
.60 Q1 Q2
Quantity (million doz eggs per week)
What happens to equilibrium price and output after the Easter season?

44. Effects of a Change in Supply
If Supply decreases, the equilibrium price will rise and the equilibrium quantity will fall.
If Supply increases, the equilibrium price will fall and the equilibrium quantity will rise.

45. Market Adjustment to a Decrease in Supply
Consider the market for romaine lettuce.
Market Adjustment to a Decrease in Supply
Prior to a season of adverse weather affecting the yield of the market, an equilibrium exists where Supply equals Demand1 with a market price of $1.80 and output of Q1.
Price ($ per head)
Supply2
2.40
2.20
Demand1
When the season of adverse weather arrives the supply of romaine lettuce falls, decreasing the supply from supply1 to supply2. What happens to the equilibrium price and output level?
Supply1
2.00 `
1.80
At $1.80 a head the quantity demanded exceeds the quantity supplied. There is upward pressure on price inducing the existing consumers to decrease their quantity demanded to Q2, drawing up the equilibrium price to $2.00.
1.60 Q2 Q1
What happens to equilibrium price and output when the weather returns to normal?
Quantity (million heads lettuce per week)

46. 7. Time and the Adjustment Process

47. Time and the Adjustment Process
With the passage of time, the market adjustments of both producers and consumers will be more complete.
Both demand and supply are more elastic in the long run than in the short run.

48. Time and Adjustment to Increase in Demand
Consider the market for laptop computers.
We begin in the short run in equilibrium at output level Q1 and price level P1.
SupplySR
Price
Demand2
SupplyLR
When the demand for laptops unexpectedly increases from demand1 to demand2, suppliers do there best to increase product in the market, pushing the price level upward to P2. What happens to the equilibrium price and output in the long run, after suppliers have a chance to change their capacity?
Demand1 P2 P3 ` P1
With time suppliers expand output pivoting the supply curve to its long run representation. The new equilibrium is where demand equals supply. The result, a further increase in equilibrium output, to Q3, and a reduction in the equilibrium price to P3. Q1 Q2 Q3
Quantity

49. 8. Invisible Hand Principle

50. Invisible Hand
Invisible hand- the tendency of market prices to direct individuals pursuing their own interest into productive activities that also promote the economic well-being of society.

51. Communicating Information
Product prices communicate up-to- date information about the consumers’ valuation of additional units of each commodity.
Without the information provided by market price it would be impossible for decision-makers to determine how intensely a good was desired relative to its opportunity cost.

52. Coordinating Actions of Market Participants
Price changes bring the decisions of buyers and sellers into harmony.
Price changes create profits and losses which change production levels for various products.

53. Prices and Market Order
Market order is the result of market prices, not central planning.

54. Qualifications
The efficiency of market organization is dependent upon:
The presence of competitive markets.
Well-defined and enforced private property rights.

55. Questions for Thought:
1. A drought during the summer of 1988 sharply reduced the 1988 output of wheat, corn, soybeans, and hay. Indicate the expected impact of the drought on the following: a. Prices of feed grains and hay during the summer of ‘88. b. Price of cattle during the fall of ‘ (Hint: What has happened to the opportunity cost of maintaining cattle during the upcoming winter?) c. Price of cattle during the summer and fall of ‘89.
2. What is the “invisible hand” principle? Does it indicate that “good intentions” are necessary if one’s actions are going to be beneficial to others?

56. End Chapter 3