范里安 微观经济学：现代观点(第一章)

Elaboration of the Basic Model: Taxation Policy Analysis
Local
government taxes apartment owners. What happens to – price – quantity of close apartments rented? Is any of the tax “passed” to renters?
Market Equilibrium
p
Higher demand causes higher market price; same quantity traded.
pe
100
QD,QS
More Comparative Statics (Do Them Yourself)
Suppose
there were more close apartments. Or, renters’ income rises;
p
p1 =$500 p2 =$490 p3 =$475
12 3
100
QD,QS
Discriminatory Monopolistic Market Equilibrium
p
p1 =$500 p2 =$490 p3 =$475
12 3
100
QD,QS
Discriminatory Monopolistic Market Equilibrium

An Illustration: Modeling the Apartment Market
Purpose:
How are apartment rents determined? Are rents “desirable”? Simplifying assumptions: – apartments are close or distant, but otherwise identical – distant apartments rents are exogenous (外生变量） and known – many potential renters and landlords
Comparative Statics
Suppose
the price of distant apartment rises. Demand for close apartments increases (rightward shift), causing A higher price for close apartments.
The Purpose of an Economic Model
The purpose of an economic model is to help provide precise insights (精 确的洞察力）on a specific economic phenomenon. Thus: – Different phenomena needs different model; – Simplification by assumption is necessary
Imperfectly Competitive Market Case 1： A Monopolistic Landlord
Landlord
sets a rental price p he rents D(p) apartments. Revenue = pD(p). He chooses p to maximizes p D(p), subject to D(p) <= S (total number of apartments in his hands) Typically, his optimal p is such that D(p) < S, that is, there are vacant apartments.
Market Demand Curve for Apartments
p
QD
Modeling Apartment Supply
Supply:
It takes time to build more close apartments so in this short-run the quantity available is fixed (at say 100).
Modeling Apartment Demand
The
Байду номын сангаас
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.
Pareto Efficiency （帕累托效率）
Two Very Common Modeling Assumptions
– Rational Choice (理性选择）: Each person tries to choose the best alternative available to him or her. – Equilibrium （均衡）: economic agents interact with each other, resulting in an equilibrium, in which each person reaches an optimal decision given others’ decisions.
Chapter One
The Market --- Appreciating Economic Modeling
The Purpose of this Chapter
To
begin to understand the art of building an economic model To begin to understand three basic elements of modeling in economics: – Purpose – Simplification through assumptions – Value judgment
Discriminatory Monopolistic Market Equilibrium
p
p1 =$500
1
100
QD,QS
Discriminatory Monopolistic Market Equilibrium
p
p1 =$500 p2 =$490
12
100
QD,QS
Discriminatory Monopolistic Market Equilibrium
Modeling Apartment Demand
Demand:
Suppose the most any one person is willing to pay to rent a close apartment is $500/month. Then p = $500 QD = 1. Suppose the price has to drop to $490 before a 2nd person would rent. Then p = $490 QD = 2.
pe 100
QD,QS
Comparative Statics （静态比较分析）
What
is exogenous in the model? – price of distant apartments – quantity of close apartments – incomes of potential renters. What happens if these exogenous variables change? Note： We are not analyzing the transition process or dynamic process.
pe
pmax
Excess demand
100
QD,QS
Value Judgement （价值判断）
Which
of the following is better? – Rent control – Perfect competition – Monopoly – Discriminatory monopoly But, what do you mean by “better”?
pe
12 3
100
QD,QS
Rent Control (房租管制）
Local
government imposes a maximum legal price, pmax < pe, the competitive price.
Market Equilibrium
p
The 100 close apartments are no longer allocated by willingness-to-pay (lottery, lines, large families first?).
Middle price
100
QD,QS
Imperfectly Competitive Market Case 2： Perfectly Discriminatory Monopolistic Landlord
Imagine
the monopolist knew everyone’s willingness-to-pay. Charge $500 to the most willing-topay, charge $490 to the 2nd most willingto-pay, etc.
p
p1 =$500 p2 =$490 p3 =$475 Discriminatory monopolist charges the competitive market price to the last renter, and rents the competitive quantity of close apartments.
Market Supply Curve for Apartments
p
100
QS
Competitive Market Equilibrium (竞争性市场均衡）
Quantity
demanded = quantity available price will neither rise nor fall so the market is at a competitive equilibrium.
Monopolistic Market Equilibrium
p Middle price, medium quantity demanded, larger revenue. Monopolist does not rent all the close apartments.
Vacant close apartments.
Competitive Market Equilibrium
p
People willing to pay pe for close apartments get close apartments. People not willing to pay pe for close apartments get distant apartments.
Taxation Policy Analysis
Market
supply is unaffected. Market demand is unaffected. So the competitive market equilibrium is unaffected by the tax. Price and the quantity of close apartments rented are not changed. Landlords pay all of the tax.