《中级微观经济学》pr8e-ch02lych

* of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. 2.1 Supply and Demand 2.2 The Market Mechanism 2.3 Changes in Market Equilibrium 2.4 Elasticities of Supply and Demand 2.5 Short-Run versus Long-Run Elasticities 2.6 Understanding and Predicting the Effects of Changing Market Conditions 2.7 Effects of Government Intervention Price Controls C H A P T E R 2 Prepared by: Fernando Quijano, Illustrator 供应和需求的基 础 2.1 供应和需求 2.2 市场机制 2.3 市场均衡的变动 2.4 供应和需求的弹性 2.5 短期弹性和长期弹性 2.6 理解并预测市场状况改变所造成 的结果 2.7政府干预 -价格控制的效应 CHAPTER OUTLINE 2 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. 供应与需求 2.1 供给曲线（ Supply Curve）：在其他影响某商品供给 的因素不变的情况下对应于每一给定的价格 .生产者所 愿意生产的该商品的数量。 QS = QS(P | .) 如果生产成本下降、 供给曲线向右移动。 3 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. OTHER VARIABLES THAT AFFECT SUPPLY 其他影响因素 QS = QS(P | cost, . ) 供给量还依赖于出价格以外的其他因素，比如，厂商所愿意 出售的商品量不但取决于他们所面临的价格，而且还取决于 他们的 生产成本 ，这些生产成本包括工资、利率和原材料的 成本。 当生产成本下降时，不管在哪个价格点，长处都会增加，从 而整条 供给曲线会右移 。 经济学家常常用供给的变动来表示供给曲线的移动，而用供 给量的变动表示供给曲线上的移动。 4 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. 收人上升，需求曲 线向右移动。 QD = QD(P) QD = QD(P | income, taste,.) 供应与需求 2.1 需求曲线 5 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. SHIFTING THE DEMAND CURVE 收人水平 增加 6 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. 替代品 两种商品，当一种商品价格上升会 导致另一种商品的需求量增加时，我们称两 种商品是替代品。 7 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. The Market Mechanism 2.2 8 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. When the supply curve shifts to the right, the market clears at a lower price P3 and a larger quantity Q3. FIGURE 2.4 Changes in Market Equilibrium 市场均衡的变动 2.3 9 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. When the demand curve shifts to the right, the market clears at a higher price P3 and a larger quantity Q3. FIGURE 2.5 10 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. SHIFTS IN SUPPLY AND DEMAND FIGURE 2.6 11 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. 弹性 反映了当某自变量上升 1%时，因变量将会发生的百 分比变化 price elasticity of demand Percentage change in quantity demanded of a good resulting from a 1-percent increase in its price. (2.1) Elasticities of Supply and Demand 供给和需求的弹性 2.4 PQ QP PP QQE p / / 12 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. LINEAR DEMAND CURVE 线性需求曲线 FIGURE 2.11 bPaQ 13 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. infinitely elastic demand LY: not exactly horizontal is easier to undersand LINEAR DEMAND CURVE 14 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. completely inelastic demand Principle that consumers will buy a fixed quantity of a good regardless of its price. FIGURE 2.12 LINEAR DEMAND CURVE 15 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. income elasticity of demand Percentage change in the quantity demanded resulting from a 1-percent increase in income. OTHER DEMAND ELASTICITIES 其他需求弹性 cross-price elasticity of demand Percentage change in the quantity demanded of one good resulting from a 1- percent increase in the price of another. 供给的价格弹性 price elasticity of supply Percentage change in quantity supplied resulting from a 1-percent increase in price. (2.2) (2.3) I Q Q I II QQE I / / m b b m mm bb PQ P Q Q P PP QQE mb / / 16 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. point elasticity of demand Price elasticity at a particular point on the demand curve. 需求的点弹性 需求曲线上某个特定点处的需求价格弹性 。 LY ： relatively derivetive Point versus Arc Elasticities arc elasticity of demand Price elasticity calculated over a range of prices. 需求的弧弹性 即在某个价格区间的弹性值。 . (2.4) )/)(/( : e la s t ic it y A r c QPPQE p 17 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. Short-Run versus Long-Run (skipped) LY This section is bad , so far, we assume the world is a point, and adjustment is instantly 2.5 18 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. FITTING LINEAR SUPPLY AND DEMAND CURVES TO DATA Understanding and Predicting the Effects of Changing Market Conditions 2.6 19 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. derive b and d derive a ( and c) Demand: Q = a bP Supply: Q = c + dP E = (P/Q)(Q/P) Demand: ED = b(P*/Q*) Supply: ES = d(P*/Q*) a = Q* + bP* (2.5a) (2.5b) (2.6a) (2.6b) (2.7) 20 of 49 Copyright 2013 Pearson Education, Inc. Microeconomics Pindyck/Rubinfeld, 8e. EFFECTS OF PRICE CONTROLS .如果没有价格控制， 市场在均衡价格 P0和 均衡数量 Q0处出清。 如果价格被控制在不 得高于 Pmax, 则供给降 至 Q1, 需求升至 Q2, 这 样就会出现短期。 Effects of Government Intervention 政府干预 -价格控制的效应 2.7