2 SUPPLY AND DEMAND I: HOW MARKETS WORK
Copyright © 2004 South-Western 4 The Market Forces of Supply and Demand
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.
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
Copyright © 2004 South-Western MARKETS AND COMPETITION Buyers determine demand. Sellers determine supply
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.
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
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
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.
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.
Copyright © 2004 South-Western Catherines Demand Schedule
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.
Figure 1 Catherines Demand Schedule and Demand Curve Copyright © 2004 South-Western Price of Ice-Cream Cone Quantity of Ice-Cream Cones $ A decrease in price increases quantity of cones demanded.
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.
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.
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 $ Changes in Quantity Demanded
Copyright © 2004 South-Western Shifts in the Demand Curve Consumer income Prices of related goods Tastes Expectations Number of buyers
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.
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,D 3 Demand curve,D 1 Demand curve,D 2 0
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.
Copyright © 2004 South-Western $ Price of Ice- Cream Cone Quantity of Ice-Cream Cones 0 Increase in demand An increase in income... D1D1 D2D2 Consumer Income Normal Good
Copyright © 2004 South-Western $ Price of Ice- Cream Cone Quantity of Ice-Cream Cones 0 Decrease in demand An increase in income... D1D1 D2D2 Consumer Income Inferior Good
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.
Table 1 Variables That Influence Buyers 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.
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.
Copyright © 2004 South-Western Bens Supply Schedule
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.
Figure 5 Bens Supply Schedule and Supply Curve Copyright©2003 Southwestern/Thomson Learning Price of Ice-Cream Cone Quantity of Ice-Cream Cones $ An increase in price increases quantity of cones supplied.
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.
Copyright © 2004 South-Western Shifts in the Supply Curve Input prices Technology Expectations Number of sellers
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.
Copyright © 2004 South-Western 1 5 Price of Ice- Cream Cone Quantity of Ice-Cream Cones 0 S 1.00 A C $3.00 A rise in the price of ice cream cones results in a movement along the supply curve. Change in Quantity Supplied
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.
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,S 3 curve, Supply S 1 curve,S 2
Table 2 Variables That Influence Sellers 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.
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.
Copyright © 2004 South-Western At $2.00, the quantity demanded is equal to the quantity supplied! SUPPLY AND DEMAND TOGETHER Demand ScheduleSupply Schedule
Figure 8 The Equilibrium of Supply and Demand Copyright©2003 Southwestern/Thomson Learning Price of Ice-Cream Cone Quantity of Ice-Cream Cones 13 Equilibrium quantity Equilibrium price Equilibrium Supply Demand $2.00
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 $
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.
Copyright © 2004 South-Western Equilibrium Shortage When price 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.
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 $ Shortage
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.
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.
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 resulting in a higher price Hot weather increases the demand for ice cream New equilibrium $
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.
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 S1S1 S2S resulting in a higher price of ice cream An increase in the price of sugar reduces the supply of ice cream and a lower quantity sold $2.50 4
Table 4 What Happens to Price and Quantity When Supply or Demand Shifts? 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.
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.
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.
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.
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.