Microeconomics I partie 1/9

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Cartes-fiches 40
Langue English
Catégorie Economie politique
Niveau Université
Crée / Actualisé 31.05.2019 / 02.10.2023
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STWE: Can a Pareto efficient allocation be achieved as a competitive equilibrium?

Yes, if preferences are convex
 

FTWE does not hold in 

the presence of externalities

FTWE focuses on efficiency, not fairness

Allocation where one person owns everything is Pareto efficient

The FTWE tells us that

the resulting equilibrium from these independent, self-interested and decentralised actions is efficient

This is the nature of the “Invisible Hand” of Adam Smith

Implicit assumptions of the FTWE: Each consumer knows only

his own tastes, endowment and the market prices

FTWE

any competitive equilibrium is Pareto efficient

Using Walras’ Law we can show that 

if demand equals supply in one market, the same must be true in the other market.

Walras’ law states that

the value of aggregate excess demands is always 0 (at any prices), i.e

In equilibrium the aggregate excess demand for each good

Aggregate excess demand for good 1

Net/Excess demand of consumer A for good 1

The Algebra of Equilibrium

Equilibrium is a set of prices (p1*;p2*) such that

total demand for each good equals total supply

Competitive Equilibrium: we must have

 

A competitive equilibrium is

an allocation E* and a set of prices, p1* and p2*, such that, given these prices (and given the initial endowments), each consumer is maximising his/her utility at that allocation

Edgeworth Box: adjustment to equilibrium

Edgeworth Box: Disequilibrium

Economic Problem
Given initial endowments, what is the allocation that ensures that

consumers maximise their utility
demand equals supply in all markets

Trade and Pareto Efficiency: The Core

Contract curve (Pareto set)

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Edgeworth-Bowley Box: Pareto Efficiency

Pareto Efficiency

A Pareto efficient allocation is such that

there is no way to make all the people involved better off

there is no way to make some individual better off without making someone else worse off

all the gains from trade have been exhausted

there are no mutually advantageous trades to be made

Pareto improvement and trade

Pareto-improving allocation

An allocation of the endowment that improves the welfare of a consumer without reducing the welfare of another

Edgeworth-Bowley Box: Trade

All points in the box, including the boundary, represent

feasible allocations of the combined endowment

Edgeworth-Bowley Box: Endowment

Feasible allocation

xA1 + xB1 < wA1 + wB1 and xA2 + xB2 < wA2 + wB2

general equilibrium analysis

Prices of other goods may/will affect people’s demands and supplies for a particular good (e.g. substitutes, complements ...)

In exchange, we relax some assumptions

Identical consumers
Exogenous prices

Differents payoffs

Oligopoly: Comparing the outcomes

Monopoly / Collusion VS Cournot VS Stackelberg

Collusion

The Stackelberg equilibrium

Leader’s profit-maximizing output, Follower's profit-maximizing output, Individuals output, Industry output

The leader's problem

The follower's problem

Stackelberg Competition: Example
Consider an industry which is characterised as follows:
Two firms producing an identical good
(Inverse) demand is given by: p(y) = a - by = a - b(y1 + y2)
Each firm has a zero marginal cost
Firm 1 has a first-mover advantage
Find the Stackelberg equilibrium (y1;y2) for this industry.

Solve the follower’s problem to obtain the reaction function.
2 Solve the leader’s problem.

Stackelberg Competition: Main Assumptions

Sequential quantity setting
Two firms producing identical product
Assume firm 1 chooses its quantity first. Firm 2 observes q1 and then chooses q2.
! Backward solution: Solve firm 2’s problem first as firm 1 (the leader) needs to anticipate the follower’s reactions.