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The Market Forces of Supply and Demand
- 1. 2 SUPPLY AND DEMAND I: HOW MARKETS WORK
- 2. Copyright © 2004 South-Western 44The Market Forces of Supply and Demand
- 3. Copyright © 2004 South-Western • Supply and demand are the two words that economists use most often. • Supply and demand are the forces that make market economies work. • Modern microeconomics is about supply, demand, and market equilibrium.
- 4. Copyright © 2004 South-Western • A market is a group of buyers and sellers of a particular good or service. • The terms supply and demand refer to the behavior of people . . . as they interact with one another in markets. MARKETS AND COMPETITION
- 5. Copyright © 2004 South-Western MARKETS AND COMPETITION • Buyers determine demand. • Sellers determine supply
- 6. Copyright © 2004 South-Western Competitive Markets • A competitive market is a market in which there are many buyers and sellers so that each has a negligible impact on the market price.
- 7. Copyright © 2004 South-Western • Perfect Competition • Products are the same • Numerous buyers and sellers so that each has no influence over price • Buyers and Sellers are price takers • Monopoly • One seller, and seller controls price Competition: Perfect and Otherwise
- 8. Copyright © 2004 South-Western • Oligopoly • Few sellers • Not always aggressive competition • Monopolistic Competition • Many sellers • Slightly differentiated products • Each seller may set price for its own product Competition: Perfect and Otherwise
- 9. Copyright © 2004 South-Western DEMAND • Quantity demanded is the amount of a good that buyers are willing and able to purchase. • Law of Demand • The law of demand states that, other things equal, the quantity demanded of a good falls when the price of the good rises.
- 10. Copyright © 2004 South-Western The Demand Curve: The Relationship between Price and Quantity Demanded • Demand Schedule • The demand schedule is a table that shows the relationship between the price of the good and the quantity demanded.
- 11. Copyright © 2004 South-Western Catherine’s Demand Schedule
- 12. Copyright © 2004 South-Western The Demand Curve: The Relationship between Price and Quantity Demanded • Demand Curve • The demand curve is a graph of the relationship between the price of a good and the quantity demanded.
- 13. Figure 1 Catherine’s Demand Schedule and Demand Curve Copyright © 2004 South-Western Price of Ice-Cream Cone 0 2.50 2.00 1.50 1.00 0.50 1 2 3 4 5 6 7 8 9 10 11 Quantity of Ice-Cream Cones $3.00 12 1. A decrease in price ... 2. ... increases quantity of cones demanded.
- 14. Copyright © 2004 South-Western Market Demand versus Individual Demand • Market demand refers to the sum of all individual demands for a particular good or service. • Graphically, individual demand curves are summed horizontally to obtain the market demand curve.
- 15. Copyright © 2004 South-Western Shifts in the Demand Curve • Change in Quantity Demanded • Movement along the demand curve. • Caused by a change in the price of the product.
- 16. Copyright © 2004 South-Western 0 D Price of Ice- Cream Cones Quantity of Ice-Cream Cones A tax that raises the price of ice-cream cones results in a movement along the demand curve. A B 8 1.00 $2.0 0 4 Changes in Quantity Demanded
- 17. Copyright © 2004 South-Western Shifts in the Demand Curve • Consumer income • Prices of related goods • Tastes • Expectations • Number of buyers
- 18. Copyright © 2004 South-Western Shifts in the Demand Curve • Change in Demand • A shift in the demand curve, either to the left or right. • Caused by any change that alters the quantity demanded at every price.
- 19. Figure 3 Shifts in the Demand Curve Copyright©2003 Southwestern/Thomson Learning Price of Ice-Cream Cone Quantity of Ice-Cream Cones Increase in demand Decrease in demand Demand curve, D3 Demand curve, D1 Demand curve, D2 0
- 20. Copyright © 2004 South-Western Shifts in the Demand Curve • Consumer Income • As income increases the demand for a normal good will increase. • As income increases the demand for an inferior good will decrease.
- 21. Copyright © 2004 South-Western $3.0 0 2.50 2.00 1.50 1.00 0.50 21 3 4 5 6 7 8 9 10 1211 Price of Ice- Cream Cone Quantity of Ice-Cream Cones0 Increase in demand An increase in income... D1 D2 Consumer Income Normal Good
- 22. Copyright © 2004 South-Western $3.0 0 2.50 2.00 1.50 1.00 0.50 21 3 4 5 6 7 8 9 10 1211 Price of Ice- Cream Cone Quantity of Ice-Cream Cones0 Decrease in demand An increase in income... D1D2 Consumer Income Inferior Good
- 23. Copyright © 2004 South-Western Shifts in the Demand Curve • Prices of Related Goods • When a fall in the price of one good reduces the demand for another good, the two goods are called substitutes. • When a fall in the price of one good increases the demand for another good, the two goods are called complements.
- 24. Table 1 Variables That Influence Buyers Copyright©2004 South-Western
- 25. Copyright © 2004 South-Western SUPPLY • Quantity supplied is the amount of a good that sellers are willing and able to sell. • Law of Supply • The law of supply states that, other things equal, the quantity supplied of a good rises when the price of the good rises.
- 26. Copyright © 2004 South-Western The Supply Curve: The Relationship between Price and Quantity Supplied • Supply Schedule • The supply schedule is a table that shows the relationship between the price of the good and the quantity supplied.
- 27. Copyright © 2004 South-Western Ben’s Supply Schedule
- 28. Copyright © 2004 South-Western The Supply Curve: The Relationship between Price and Quantity Supplied • Supply Curve • The supply curve is the graph of the relationship between the price of a good and the quantity supplied.
- 29. Figure 5 Ben’s Supply Schedule and Supply Curve Copyright©2003 Southwestern/Thomson Learning Price of Ice-Cream Cone 0 2.50 2.00 1.50 1.00 1 2 3 4 5 6 7 8 9 10 11 Quantity of Ice-Cream Cones $3.00 12 0.50 1. An increase in price... 2. ... increases quantity of cones supplied.
- 30. Copyright © 2004 South-Western Market Supply versus Individual Supply • Market supply refers to the sum of all individual supplies for all sellers of a particular good or service. • Graphically, individual supply curves are summed horizontally to obtain the market supply curve.
- 31. Copyright © 2004 South-Western Shifts in the Supply Curve • Input prices • Technology • Expectations • Number of sellers
- 32. Copyright © 2004 South-Western Shifts in the Supply Curve • Change in Quantity Supplied • Movement along the supply curve. • Caused by a change in anything that alters the quantity supplied at each price.
- 33. Copyright © 2004 South-Western 1 5 Price of Ice- Cream Cone Quantity of Ice-Cream Cones0 S 1.00 A C $3.0 0 A rise in the price of ice cream cones results in a movement along the supply curve. Change in Quantity Supplied
- 34. Copyright © 2004 South-Western Shifts in the Supply Curve • Change in Supply • A shift in the supply curve, either to the left or right. • Caused by a change in a determinant other than price.
- 35. Figure 7 Shifts in the Supply Curve Copyright©2003 Southwestern/Thomson Learning Price of Ice-Cream Cone Quantity of Ice-Cream Cones 0 Increase in supply Decrease in supply Supply curve, S3 curve, Supply S1 Supply curve, S2
- 36. Table 2 Variables That Influence Sellers Copyright©2004 South-Western
- 37. Copyright © 2004 South-Western SUPPLY AND DEMAND TOGETHER • Equilibrium refers to a situation in which the price has reached the level where quantity supplied equals quantity demanded.
- 38. Copyright © 2004 South-Western SUPPLY AND DEMAND TOGETHER • Equilibrium Price • The price that balances quantity supplied and quantity demanded. • On a graph, it is the price at which the supply and demand curves intersect. • Equilibrium Quantity • The quantity supplied and the quantity demanded at the equilibrium price. • On a graph it is the quantity at which the supply and demand curves intersect.
- 39. Copyright © 2004 South-Western At $2.00, the quantity demanded is equal to the quantity supplied! SUPPLY AND DEMAND TOGETHER Demand Schedule Supply Schedule
- 40. Figure 8 The Equilibrium of Supply and Demand Copyright©2003 Southwestern/Thomson Learning Price of Ice-Cream Cone 0 1 2 3 4 5 6 7 8 9 10 11 12 Quantity of Ice-Cream Cones 13 Equilibrium quantity Equilibrium price Equilibrium Supply Demand $2.00
- 41. Figure 9 Markets Not in Equilibrium Copyright©2003 Southwestern/Thomson Learning Price of Ice-Cream Cone 0 Supply Demand (a) Excess Supply Quantity demanded Quantity supplied Surplus Quantity of Ice-Cream Cones 4 $2.50 10 2.00 7
- 42. Copyright © 2004 South-Western Equilibrium • Surplus • When price > equilibrium price, then quantity supplied > quantity demanded. • There is excess supply or a surplus. • Suppliers will lower the price to increase sales, thereby moving toward equilibrium.
- 43. Copyright © 2004 South-Western Equilibrium • Shortage • When price < equilibrium price, then quantity demanded > the quantity supplied. • There is excess demand or a shortage. • Suppliers will raise the price due to too many buyers chasing too few goods, thereby moving toward equilibrium.
- 44. Figure 9 Markets Not in Equilibrium Copyright©2003 Southwestern/Thomson Learning Price of Ice-Cream Cone 0 Quantity of Ice-Cream Cones Supply Demand (b) Excess Demand Quantity supplied Quantity demanded 1.50 10 $2.00 74 Shortage
- 45. Copyright © 2004 South-Western Equilibrium • Law of supply and demand • The claim that the price of any good adjusts to bring the quantity supplied and the quantity demanded for that good into balance.
- 46. Copyright © 2004 South-Western Three Steps to Analyzing Changes in Equilibrium • Decide whether the event shifts the supply or demand curve (or both). • Decide whether the curve(s) shift(s) to the left or to the right. • Use the supply-and-demand diagram to see how the shift affects equilibrium price and quantity.
- 47. Figure 10 How an Increase in Demand Affects the Equilibrium Copyright©2003 Southwestern/Thomson Learning Price of Ice-Cream Cone 0 Quantity of Ice-Cream Cones Supply Initial equilibrium D D 3. . . . and a higher quantity sold. 2. . . . resulting in a higher price . . . 1. Hot weather increases the demand for ice cream . . . 2.00 7 New equilibrium$2.50 10
- 48. Copyright © 2004 South-Western Three Steps to Analyzing Changes in Equilibrium • Shifts in Curves versus Movements along Curves • A shift in the supply curve is called a change in supply. • A movement along a fixed supply curve is called a change in quantity supplied. • A shift in the demand curve is called a change in demand. • A movement along a fixed demand curve is called a change in quantity demanded.
- 49. Figure 11 How a Decrease in Supply Affects the Equilibrium Copyright©2003 Southwestern/Thomson Learning Price of Ice-Cream Cone 0 Quantity of Ice-Cream Cones Demand New equilibrium Initial equilibrium S1 S2 2. . . . resulting in a higher price of ice cream . . . 1. An increase in the price of sugar reduces the supply of ice cream. . . 3. . . . and a lower quantity sold. 2.00 7 $2.50 4
- 50. Table 4 What Happens to Price and Quantity When Supply or Demand Shifts? Copyright©2004 South-Western
- 51. Copyright © 2004 South-Western Summary • Economists use the model of supply and demand to analyze competitive markets. • In a competitive market, there are many buyers and sellers, each of whom has little or no influence on the market price.
- 52. Copyright © 2004 South-Western Summary • The demand curve shows how the quantity of a good depends upon the price. • According to the law of demand, as the price of a good falls, the quantity demanded rises. Therefore, the demand curve slopes downward. • In addition to price, other determinants of how much consumers want to buy include income, the prices of complements and substitutes, tastes, expectations, and the number of buyers. • If one of these factors changes, the demand curve shifts.
- 53. Copyright © 2004 South-Western Summary • The supply curve shows how the quantity of a good supplied depends upon the price. • According to the law of supply, as the price of a good rises, the quantity supplied rises. Therefore, the supply curve slopes upward. • In addition to price, other determinants of how much producers want to sell include input prices, technology, expectations, and the number of sellers. • If one of these factors changes, the supply curve shifts.
- 54. Copyright © 2004 South-Western Summary • Market equilibrium is determined by the intersection of the supply and demand curves. • At the equilibrium price, the quantity demanded equals the quantity supplied. • The behavior of buyers and sellers naturally drives markets toward their equilibrium.
- 55. Copyright © 2004 South-Western Summary • To analyze how any event influences a market, we use the supply-and-demand diagram to examine how the even affects the equilibrium price and quantity. • In market economies, prices are the signals that guide economic decisions and thereby allocate resources.