Market demand refers to the sum of all individual demands for a particular good or service.市场需求 是 指所有个人对某种物品或劳务需求的 总和。 Graphically, individual demand curves are summed horizontally to obtain the market demand curve. 从图形上看, 把个人需求曲线水平相 加，就得出了市场需求曲线。
第二章 供给与需求（I）：市场如何运行 SUPPLY AND DEMAND I: HOW MARKETS WORK
“你可以使一只鹦鹉成为经济学家，但前 提必须是让它明白‘供给’和‘需求’ 。”
----------------萨缪尔逊《经济学》
思考：
1、农业的好消息是否是农民的好消息？ 2、最低工资法是否是保障工人福利的好 制度？
需求曲线——把价格与需求量联系在 一起的向右下方倾斜的曲线。
Figure 1 Catherine’s Demand Schedule and Demand Curve （Catherine’s的需求表和需求曲线）
Ice-CreaPmriCceonoef 冰激凌蛋卷的价格
$3.00
2.50
1. A decrease in price ...
The demand schedule is a table that shows the relationship between the price of the good and the quantity demanded. 需求表 —— 表示一种物品的价格 与需求量之间关系的表格。
Catherine’s Demand Schedule
Law of Demand 需求规律
The law of demand states that there is an inverse relationship between price and quantity demanded. 需求规律认为，价格与需求量之间 的关系是负关系。
Demand Schedule 需求表
Change in Quantity Demanded versus Change in Demand 需求量的变化与需求的变化
Change in Quantity Demanded(需求量的变化）
Caused by a change in the price of the product.(是由于 产品价格变动引起的)。
Competitive Market完全竞争市场
Products are the same Numerous buyers and sellers so that each has no influence over price Buyers and Sellers are price takers
make market economies work.）
（ Modern microeconomics is about supply, demand, and market equilibrium. ）现代微 观经济学就是关于供给、需求和市场均衡的 学科。
Markets and competition 市场与竞争
2.00
1.50
1.00
0.50
0 1 2 3 4 5 6 7 8 9 10 11 12 Quantity of
Ice-Cream Cones
2. ... increases quantity 冰激淋蛋卷的数量
of cones demanded.
Market Demand versus Individual Demand 市场需求和单个消费者需求
供给与需求的市场力量
供给和需求是经济学家最常用的两个词。（
Supply and demand are the two words that economists use most often ）
供给和需求是让市场经济运行的力量。
（Supply and demand are the forces that
垄断 一个卖者，卖者决定价格。
寡头 少数几个卖者。 并不总是主动地进行竞争。
Demand 需求
Quantity demanded is the amount of a good that buyers are willing and able to purchase. 需求量是指买者愿意而且能够购 买的一种物品或劳务的数量。
产品是完全相同的。 买者和卖者如此之多，以至于没有一个 买者或卖者可以影响价格。 买者和卖者都是价格接受者。
Competition: Perfect and Otherwise
Monopoly One seller, and seller controls price
Oligopoly Few sellers Not always aggressive competition
凯瑟琳的需求表
Pபைடு நூலகம்ric e
价格
$ 0 .0 0 0 .5 0 1 .0 0 1 .5 0 2 .0 0 2 .5 0 3 .0 0
Q u a n tity
数量
12 10 8 6 4 2 0
Demand Curve 需求曲线
The demand curve is the downwardsloping line relating price to quantity demanded.
Buyers determine demand. 买者决定需求
Sellers determine supply. 卖者决定供给
A Competitive Market 完全竞争市场
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 竞争市场——有很多买者和卖者的 市场，所以每一个买者或卖者对市 场价格的影响都可以忽略不计。