范里安微观经济学英文版

Cost Minimizing Input Choice
How does a firm select inputs to produce a given output at minimum cost? Assumptions

◦ Two Inputs: Labor (L) and capital (K) ◦ Price of labor: wage rate (w) ◦ The price of capital (r)
In the short run, some costs are fixed In the long run, firm can change anything including plant size

◦ Can produce at a lower average cost in long run than in short run ◦ Capital and labor are both flexible
input added to the production process will add an equivalent amount of output.
MPL
MPK
Cost in the Long Run

Cost minimization with Varying Output Levels
Q1
C2
Labor per year
Input Substitution When an Input Price Change
If the price of labor changes, then the slope of the isocost line changes, -(w/r) It now takes a new quantity of labor and capital to produce the output If price of labor increases relative to price of capital, and capital is substituted for labor

– 谁将得到住房？ – 各种类型的市场机制将提供多少住房？ – 垄断市场供应的住房比竞争市场供应的是多 还是少? – 房租管制是增加还是减少了住房的均衡数量? – 哪一种经济机制将提供帕雷托有效的住房数 量?
小节（知识点）
• 经济学是通过对社会现象建立模型进行研究的， 这种模型能对现实社会作简化的描述。 • 在经济分析过程中，经济学家以最优化原理和 均衡原理为指导。最优化原理指的是人们总是 试图选择对他们最有利的东西；均衡原理是指 在给定其他参与者的选择下，每一个参与者的 选择都是最优的。 • 需求曲线衡量在不同价格上人们愿意购买的需 求量，供给曲线衡量不同价格时人们愿意供应 的供给量。均衡价格是需求量与供给量相等的 价格。 • 研究均衡价格和数量在基础条件变化时如何变
• 在评估一个经济机制或制度安排时，现代经济 学通常所采用的一个最重要的评估标准是看这
激励相容
• 所谓激励相容就是使自利的个人和人们之间的互利 统一起来，使得每人在追求其个人利益时，同时也 达到了其制度安排设计者所想要达到的目标。 • 检验一个经济机制或规则是否运行良好的一个基本 标准是看它能否提供内在激励使人们努力工作，激 励决策者作出有利于他主管的经济组织的好决策， 激励企业尽可能有效率地生产。
比较静态分析
• 假设外城区住房的价格提高 –内城区住房需求增加
p 高的市场需求导致高的均衡价格 ，相同的均衡数量。 课后自己还可做大量的其他比较 静态分析如：内城区住房增加、 需求者收入增加、以及政府征税 等等来研究内城区住房价格和住 户数量的变化。
Pe* pe s
QD,QS
1.7 配置住房的其他方法 —不完全竞争市场情况
–对经济现象建立模型
经济环境
• 经济环境通常由经济人、经济人的特征、经济社 会制度环境以及信息结构等组成。 – 1）参与人数量巨大（无穷大是一种考虑），并 且哪一参与人都不占有明显优势，即单个参与 人的行为客观上不会影响其他任何参与人的行 为，从而不会影响整体行为。 – 2）参与人唯一，该参与人的任何行为都等于整 体行为。 – 3）参与人数量有限而不唯一（介于1与无穷大 之间），单个参与人的行为不等于整体行为， 但能影响其他参与人的行为，从而会影响整体 行为。

-p1/p2
+1
x1
Budget Constraints
x2 Opp. cost of an extra unit of commodity 1 is p1/p2 units foregone of commodity 2. Opp. cost of an extra +1 unit of commodity 2 is -p2/p1 p2/p1 units foregone of commodity 1. x1
Chapter 3
Consumer Behavior
Consumer Behavior
1.
There are three steps involved in the study of consumer behavior Consumer Preferences
◦ To describe how and why people prefer one good to another

Budget Constraints
Commodity prices are p1, p2, … , pn. Q: When is a bundle (x1, … , xn) affordable at prices p1, … , pn? A: When p1x1 + … + pnxn m where m is the consumer‟s (disposable) income.
2.
Budget Constraints
◦ People have limited incomes
Consumer Behavior
3.
Given preferences and limited incomes, what amount and type of goods will be purchased?

The circular flow of economic activities.
product market market
factor
The product market and the factor market.
The market relation is mutual and voluntary.
•Fig.
Convexity x2
(y1,y2)
Averaged bundle
(x1,x2) x1
Chapter 4
(as a way to describe preferences)
Utilities
•Essential ordinal utilities, versus
•convenient cardinal utility functions.
m/p2
Budget line
Slope
= - p’1/p2
m/p’1
Slope = - p1/p2 m/p1
Taxes, quantity taxes, value taxes
(ad valorem taxes), and lump-sum
taxAess. ubsidy
is the opposite of a quantity tax.
commodities,
including
goods and services.
Main economic activities:
Consumption, Production, and Exchange.
Microeconomics and macroeconomics:
to show the market mechanism (the invisible hand), to supplement it.

Chapter 11
Oligopoly
Oligopoly
A monopoly is an industry consisting a single firm. An oligopoly is an industry consisting of a few firms. Particularly, each firm’s own price or output decisions affect its competitors’ profits.
75
Firm 2’s Reaction Curve Q*2(Q1) Firm 2’s reaction curve shows how much it will produce as a function of how much it thinks Firm 1 will produce.
50 x
25
F .O.C y1 f1 ( y )
e 2
Sim ilarly , y2 f 2 ( y )
e 1
Reaction Function

Reaction function
◦ It gives one firm’s optimal choice as a function of its beliefs about the other firm’s choice ◦ The relationship between a firm’s profitmaximizing output and the amount it thinks its competitor will produce ◦ A firm’s profit-maximizing output is a decreasing schedule of the expected output of the other firm

MC(y) AC(y)
Y
y3*
y
长期行业供给
行业 p
行业需求
p3’
一个典型厂商 p
S3(p) S4(p)
p3’
MC(y) AC(y)
Y
y3*
y
第四个厂商现在进入的经济利润为负。
长期行业供给
行业 p 行业需求
一个典型厂商 p
MC(y) AC(y)
S3(p)
p3’
S4(p) p3’
Y
y3*
y
第四个厂商现在进入的经济利润为零。
行业 p
行业需求
S2(p)
一个典型的厂商 p
MC(y) AC(y)
p2
p2
P>0
Y
y2*
y
每个厂商都获得正的经济利润，
吸引其它厂商进入。
长期行业供给
行业 p
行业需求
p2
S2(p) S3(p)
一个典型厂商 p
MC(y) AC(y)
p2
Y
行业供给向外移动
y2*
y
长期行业供给
行业 p
行业需求
p2
S2(p) S3(p)
为将获得负的经济利润。
y2*
y
长期行业供给
假设行业需求继续上升，行业价格也继 续上升，两个厂商都生产更多且获得更 多的经济利润—知道第三个厂商对于进 入行业与不进入行业都一样。
长期行业供给
行业 p
行业需求
S2(p) S3(p)
一个典型厂商 p
MC(y) AC(y)
p2”
p2”
Y
y2*
y
长期行业供给
一个典型厂商 p
MC(y) AC(y)

Then p = $490 QD = 2.
Modeling Apartment Demand
The lower is the rental rate p, the larger is the quantity of close apartments demanded
p QD .
The quantity demanded vs. price graph is the market demand curve for close apartments.
Modeling the Apartment Market
How are apartment rents determined? Suppose
apartments are close or distant, but otherwise identical
distant apartments rents are exogenous and known
Market Supply Curve for Apartments
p
100
QS
Competitive Market Equilibrium
“low” rental price quantity demanded of close apartments exceeds quantity available price will rise.
--- John Maynard Keynes
Economic Modeling
What causes what in economic systems?
At what level of detail shall we model an economic phenomenon?

Chapter 16 均衡
A market clears or is in equilibrium when the total quantity demanded by buyers exactly equals the total quantity supplied by sellers.
一、对均衡的理解
p
MarkMetarket MEaqrkueitlqibuarinutimty supplied is
demand
fixed, independent of price.
S(p) = c+dp, so d=0
and S(p) c.
p*
q* = c
D-1(q) = (a-q)/b q
p
MarkMetarket MEaqrkueitlqibuarinutimty supplied is
supply
q=S(p)
D(p’) < S(p’); an excess
p’
of quantity supplied over
p*
quantity demanded.
q=D(p)
D(p’)
S(p’) D(p), S(p)
Market price must fall towards p*.
p
MarkMetarket MEaqrkueitlibrium
The division of the $t between buyers and sellers is called the incidence （( 税的)负担）of the tax.
p
Market demand
Market supply
Tax paid by

A Competitive Firm – Losses
Price
C D B MC
ATC
A
P = MR AVC
q*
Output
Short Run Production

Why would a firm produce at a loss?
◦ Might think price will increase in near future ◦ Shutting down and starting up could be costly
A
P = MR AVC
F
E
q*
Output
Competitive Firm – Short Run Supply
Supply curve tells how much output will be produced at different prices Competitive firms determine quantity to produce where P = MC

Profit Maximization – Short Run
Cost, Revenue, Profit ($s per year) Profits are maximized where MR (slope at A) and MC (slope at B) are equal
C(q)
R(q)

Choosing Output: Short Run

The point where MR = MC, the profit maximizing output is chosen
◦ MR = MC at quantity, q*, of 8 ◦ At a quantity less than 8, MR > MC, so more profit can be gained by increasing output ◦ At a quantity greater than 8, MC > MR, increasing output will decrease profits

Income and Substitution Effects

Income Effect
◦ The income effect is the change in an item’s consumption brought about by the increase in purchasing power, with the price of the item held constant ◦ When a person’s income increases, the quantity demanded for the product may increase or decrease
So
* dR dX X* (p) p dp dp
Revenue and Own-Price Elasticity of Demand
Sellers’ revenue is
R(p) p X* (p).
So
* dR dX X* (p) p dp dp
dx x dp x p x
u u
_
x I I p x
Another Way of Decomposing Price Effect
Hicksian substitution effect: holding the utility constant Slutsky substitution effect: holding the purchasing power constant

Revenue and Own-Price Elasticity of Demand
Sellers’ revenue is
R(p) p X* (p).
Revenue and Own-Price Elasticity of Demand