, 2007 Thomson South-Western,市场与竞争,供给与需求是经济学家最常用的两个词。供给与需求是使市场经济运行的力量。微观经济学分析供给、需求和市场均衡。,市场是某种物品或服务的买者和卖者组成的一个群体 A market is a group of buyers and sellers of a particular good or service.,什么是市场?,什么是市场?,供给和需求是指人们在市场上进行交易时的行为买方决定需求卖方决定供给,什么是竞争?,竞争市场是指有许多买者与卖者，以至于每个人对市场价格的影响都微乎其微的市场。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.,What Is Competition?,完全竞争产品完全相同无数的买者和卖者，以至于没有任何一个买者和卖者可以影响价格买者和卖者都是价格接受者Perfect CompetitionProducts are the sameNumerous buyers and sellers so that each has no influence over priceBuyers and Sellers are price takers,What Is Competition?,垄断 只有一个卖者，卖者控制价格寡头很少卖者不存在激烈的竞争垄断竞争很多卖方微小的产品差别Slightly differentiated products每个卖方可以制定自己产品的价格,各类市场的特征,2.需求 Demand,需求量是买者愿意并且能够购买的该物品的数量。Quantity demanded is the amount of a good that buyers are willing and able to purchase.,Law of Demand Other things equal, when the price of the good rises, the quantity demanded of a good falls, and when the price falls, the quantity demanded rises. PQD,需求定理在其他条件不变时，一种物品的价格上升，对该物品的需求量减少；一种物品的价格下降，对该物品的需求量增加。,需求表Demand Schedule需求曲线Demand Curve需求函数Demand Function,如何描述需求定理,Catherine 的需求表,需求表表示一种物品的价格与需求量之间关系的表格。 Demand ScheduleThe demand schedule is a table that shows the relationship between the price of the good and the quantity demanded.,图 1 Catherine的需求表和需求曲线,冰激淋蛋卷的价格,0,2.50,2.00,1.50,1.00,0.50,1,2,3,4,5,6,7,8,9,10,11,冰激淋蛋卷的需求量,$3.00,12,需求曲线：价格和需求量之间的关系,需求曲线表示一种物品的价格与需求量之间关系的图形。Demand CurveThe demand curve is a graph of the relationship between the price of a good and the quantity demanded.,需求函数,有没有哪些物品不遵循需求定理,？,市场需求和个人需求,市场需求是所有个人对某种特定物品和劳务的需求的总和。 Market demand refers to the sum of all individual demands for a particular good or service.把个人需求曲线水平相加得到市场需求曲线。 Individual demand curves are summed horizontally to obtain the market demand curve.,市场需求曲线,冰激淋蛋卷的价格,冰激淋蛋卷的价格,冰激淋蛋卷的价格,2.00,2.00,2.00,4,3,7,1.00,1.00,1.00,8,5,13,冰激淋蛋卷的数量,冰激淋蛋卷的数量,冰激淋蛋卷的数量,Catherine的需求,Nicholas的需求,市场需求,+,=,当价格是 $2.00时, Catherine 需要4个冰激淋蛋卷。,当价格是 $2.00时, Nicholas 需要3个冰激淋蛋卷。,价格是$2.00 ，市场需求量是 7 个冰激淋蛋卷。,当价格是 $1.00时, Catherine 需要8个冰激淋蛋卷。,当价格是 $1.00时, Nicholas 需要5个冰激淋蛋卷。,价格是$1.00 ，市场需求量是 7 个冰激淋蛋卷。,Shifts in the Demand Curve 需求曲线的移动,需求量的变动Change in Quantity Demanded需求的变动Change in Demand,需求量的变动在需求曲线上点的移动 Movement along the demand curve.由产品价格的变动引起 Caused by a change in the price of the product.,0,D,冰激淋蛋卷的价格,冰激淋蛋卷的数量,对冰激淋蛋卷的销售者征税导致冰激淋价格的上升，并带来了沿着需求曲线的移动。,A,8,1.00,需求量的变化,需求的变动需求曲线的移动，向左移动或者向右移动 A shift in the demand curve, either to the left or right.在价格不变时，由改变需求量的其他因素引起 Caused by any change that alters the quantity demanded at every price.,图 3 需求曲线的移动,冰激淋蛋卷的价格,冰激淋蛋卷的数量,0,使每一个价格水平下的需求量增加的任何变动都会使需求曲线向右移动，这是需求增加。,使每一个价格水平下的需求量减少的任何变动都会使需求曲线向左移动，这是需求减少。,需求曲线的移动,消费者收入Consumer income相关产品的价格 Prices of related goods嗜好 Tastes预期 Expectations买者的数量Number of buyers,需求曲线的移动,收入随着收入的增加，正常物品的需求增加。 As income increases the demand for a normal good will increase.随着收入的增加，低档物品的需求减少。 As income increases the demand for an inferior good will decrease.,$3.00,2.50,2.00,1.50,1.00,0.50,2,1,3,4,5,6,7,8,9,10,12,11,价格,数量,0,收入增加.,D1,D2,正常物品,$3.00,2.50,2.00,1.50,1.00,0.50,2,1,3,4,5,6,7,8,9,10,12,11,价格,数量,0,收入增加.,D1,D2,低档物品,需求曲线的移动,相关物品的价格当一种物品价格下降引起对另一种物品的需求减少时，这两种物品被称为替代品。When a fall in the price of one good reduces the demand for another good, the two goods are called substitutes.当一种物品价格下降引起对另一种物品的需求增加时，这两种物品被称为互补品。When a fall in the price of one good increases the demand for another good, the two goods are called complements.,需求曲线的移动,嗜好预期 Expecting the price of a good to fall in the future, you may be less willing to buy it now.买者的数量,Table 1 Variables That Influence Buyers,以汽车为例,2.00,0,20,每包香烟的价格,每天吸的香烟量,提高香烟价格的税收引起沿着需求曲线的变动,D1,案例分析：减少香烟需求量的方法,A,C,4.00,2.00,0,20,每包香烟的价格,每天吸的香烟量,限制吸烟的政策使需求曲线向左移动,D1,D2,案例分析：减少香烟需求量的方法,A,B,3. 供给 Supply,供给量是卖者愿意并且能够出售的该物品的数量。Quantity supplied is the amount of a good that sellers are willing and able to sell.,供给定理在其他条件不变时，一种物品价格上升，该物品供给量增加；一种物品价格下降，该物品供给量也减少。Law of Supply Other things equal, the quantity supplied of a good rises when the price of the good rises. PQS,供给表Supply Schedule供给曲线Supply Curve供给函数Supply Function,如何描述供给定理,供给曲线：价格与供给量之间的关系,供给表表示一种物品的价格与供给量之间关系的表格。 Supply ScheduleThe supply schedule is a table that shows the relationship between the price of the good and the quantity supplied.,Bens Supply Schedule,供给曲线：价格与供给量之间的关系,供给曲线表示一种物品的价格与供给量之间关系的图形。Supply CurveThe supply curve is the graph of the relationship between the price of a good and the quantity supplied.,