中级微观经济学——理论与应用（第10版）（经济学经典教材·双语教学用书）尼克尔森等著0324319681_67666上课用课件.pptVIP

Chapter 4 Market Demand And Elasticity Market Demand Curves Market demand: total quantity of good or service demanded by all potential buyers. Market demand curve shows relationship between the total quantity demanded of a single good or service and its price, holding all other factors constant. Constructing the Market Demand Curve We construct a market demand curve (D) by horizontally summing the all individual consumers’ demand for the good or service. Fig. 4-1: Assume market consists of only two buyers At any given price, such as P*X, individual 1 demands X*1 and individual 2 demands X*2. FIGURE 4-1: Constructing a Market Demand Curve from Individual Demand Curves FIGURE 4-1: Constructing a Market Demand Curve from Individual Demand Curves FIGURE 4-1: Constructing Market Demand Curve from Individual Demand Curves Construction of Market Demand Curve The total QX demanded at market P*X is sum of two amounts: X* = X*1 + X*2 . Point X*, P*X provides one point on market demand curve. Other points on D curve similarly plotted based on all QX demanded at other PX. Shifts in Market Demand Curve: Income An increase in income for each consumer would shift their individual demand curves out so that the market demand curve would also shift out from the origin. Shown in Figure 4-2 FIGURE 4-2: Increases in Each Individual’s Income: Market Demand Curve Shifts Outward Shifts in Market Demand Curve: Income Some events result in ambiguous demand curve outcomes: If one consumer’s demand curve shifts out while another’s shifts in, the net effect depends on the size of the relative shifts. Income increases for pizza lovers would increase market demand for pizza, so long as pizza is normal good. Shifts in Market Demand Curve: Income If only people who don’t like pizza enjoyed income increases, the market demand curve for pizza would not change. Changes in prices of related goods-- substitutes or complements--will also shift individual and market dema