1 Entrada y salida Puntos sobresalientes 1. A medida que entran nuevas empresas a la industria, el...

1

Entrada y salida

Puntos sobresalientes

1. A medida que entran nuevas empresas a la industria, el precio cae y los beneficios económicos de cada empresa existente

disminuyen.

2. A medida que las empresas abandonan una industria, el precio se eleva y la pérdida

económica de cada empresa que permanece dentro de la industria tiende a disminuir.

2

Equilibrio de largo plazo

El equilibrio de largo plazo en una industria competitiva ocurre cuando las empresas obtienen un beneficio normal o el beneficio económico es nulo.

Por tanto, en el equilibrio de largo plazo en una industria competitiva, las empresas ni entran ni abandonan la industria, y tampoco amplían ni reducen su tamaño.

3

Competencia y eficiencia

El uso eficiente de los recursos requiere de tres condiciones:

1. Los consumidores sean eficientes

2. Las empresas sean eficientes

3. El mercado esté en equilibrio

4

Excedente del ConsumidorEl excedente del cosumidor

es una medida de las ganancias del consumidor.

Es la diferencia entre lo que esta dispuesto a pagar y lo que en realidad paga.

Ejemplo: si el consumidor valora un bien en $8, y paga solamente $4, el Excedente del consumidor es igual a 4.

5

Geometría del excedente del consumidor

6

Excedente del productor

El excedente del productor

es una medida de las ganancias del productor.

Es la diferencia entre el precio que esta dispuesto a vender y el precio que en realidad vende.

Ejemplo: si el productor valora vender el bien en $8, y lo vende paga en $10, el Excedente del productor es $2.

7

Geometría del excedente del productor

8Cantidad

Pre

cio

P*

Eficiencia de la competenciaO = CM

D

Q*

Excedente delconsumidor

Excedente del productor

B0

Asignación eficiente

C0

Q0

9

Market Equilibrium

A market is in equilibrium when total quantity demanded by buyers equals total quantity supplied by sellers.

10

Market Equilibriump

D(p)

q=D(p)

Marketdemand

11

Market Equilibriump

S(p)

Marketsupply

q=S(p)

12

Market Equilibriump

D(p), S(p)

q=D(p)

Marketdemand

Marketsupply

q=S(p)

13

Market Equilibriump

D(p), S(p)

q=D(p)

Marketdemand

Marketsupply

q=S(p)

p*

q*

14

Market Equilibriump

D(p), S(p)

q=D(p)

Marketdemand

Marketsupply

q=S(p)

p*

q*

D(p*) = S(p*); the marketis in equilibrium.

15

Market Equilibriump

D(p), S(p)

q=D(p)

Marketdemand

Marketsupply

q=S(p)

p*

S(p’)

D(p’) < S(p’); an excessof quantity supplied overquantity demanded.

p’

D(p’)

16

Market Equilibriump

D(p), S(p)

q=D(p)

Marketdemand

Marketsupply

q=S(p)

p*

S(p’)

D(p’) < S(p’); an excessof quantity supplied overquantity demanded.

p’

D(p’)

Market price must fall towards p*.

17

Market Equilibriump

D(p), S(p)

q=D(p)

Marketdemand

Marketsupply

q=S(p)

p*

D(p”)

D(p”) > S(p”); an excessof quantity demandedover quantity supplied.

p”

S(p”)

18

Market Equilibriump

D(p), S(p)

q=D(p)

Marketdemand

Marketsupply

q=S(p)

p*

D(p”)

D(p”) > S(p”); an excessof quantity demandedover quantity supplied.

p”

S(p”)

Market price must rise towards p*.

19

Market Equilibrium

An example of calculating a market equilibrium when the market demand and supply curves are linear.

D p a bp( ) S p c dp( )

20

Market Equilibriump

D(p), S(p)

D(p) = a-bp

Marketdemand

Marketsupply

S(p) = c+dp

p*

q*

21

Market Equilibriump

D(p), S(p)

D(p) = a-bp

Marketdemand

Marketsupply

S(p) = c+dp

p*

q*

What are the valuesof p* and q*?

22

Market EquilibriumD p a bp( ) S p c dp( )

At the equilibrium price p*, D(p*) = S(p*).

23


At the equilibrium price p*, D(p*) = S(p*).That is, a bp c dp * *

24



which gives pa cb d

*

25



which gives pa cb d

*

and q D p S pad bcb d

* * *( ) ( ) .

26

Market Equilibriump

D(p), S(p)

D(p) = a-bp

Marketdemand

Marketsupply

S(p) = c+dpp

a cb d

*

dbbcad

q*

27

Market Equilibrium

One special case:

1. quantity supplied is fixed, independent of the market price, and

28

Market EquilibriumMarket quantity supplied isfixed, independent of price.

p

qq*

29

Market Equilibrium

S(p) = c+dp, so d=0and S(p) c.

p

qq* = c

Market quantity supplied isfixed, independent of price.

30

Market Equilibrium


p

qq* = c

Marketdemand


D(p) = a-bp

31

Market Equilibrium


p

q

p*

D(p) = a-bp

Marketdemand

q* = c


32

Market Equilibrium


p

q

p* =(a-c)/b

Marketdemand

q* = c


D(p) = a-bp

33

Market Equilibrium


p

q

D(p) = a-bp

Marketdemand

q* = c

p* =(a-c)/b


pa cb d

*

qad bcb d

*

34

Market Equilibrium


p

q

Marketdemand

q* = cp

a cb d

*

qad bcb d

*

with d = 0 give

pa c

b*

q c* .

p* =(a-c)/b


D(p) = a-bp

35

Quantity Taxes

What is the effect of a quantity tax on a market’s equilibrium?

How are prices affected? How is the quantity traded affected? Who pays the tax? How are gains-to-trade altered?

36

Quantity Taxes Two kinds of taxes that one might

impose: quantity taxes and value taxes (ad valorem taxes)

A quantity tax is a tax levied per unit of quantity bought or sold. The gasoline tax is 12 cents a gallon.

If the consumer is paying pb =$1.50 per gallon of gasoline, the supplier is getting ps =$1.50 -.12=$1.38 per gallon.

37

Quantity Taxes

In general, if t is the amount of the quantity tax per unit sold, then

p p tb s

38

Quantity Taxes

A value tax is a tax expressed in percentage units.

sb ptp )1(

39

Quantity Taxes

Even with a tax the market must clear.

I.e. quantity demanded by buyers at price pb must equal quantity supplied by sellers at price ps.

D p S pb s( ) ( )

40

Quantity Taxes

p p tb s D p S pb s( ) ( )and

describe the market’s equilibrium.Notice these conditions apply nomatter if the tax is levied on sellers or onbuyers.

41

Quantity Taxes & Market Equilibrium

p

D(p), S(p)

Marketdemand

Marketsupply

p*

q*

No tax

42


p

D(p), S(p)

Marketdemand

Marketsupply

p*

q*

$t

An supplier taxraises the marketsupply curve by $t

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p

D(p), S(p)

Marketdemand

Marketsupply

p*

q*

An supplier taxraises the marketsupply curve by $t,raises the buyers’price and lowers thequantity traded.

$tpb

qt

44


p

D(p), S(p)

Marketdemand

Marketsupply

p*

q*

An supplier taxraises the marketsupply curve by $t,raises the buyers’price and lowers thequantity traded.

$tpb

qt

And sellers receive only ps = pb - t.

ps

45


p

D(p), S(p)

Marketdemand

Marketsupply

p*

q*

No tax

46


p

D(p), S(p)

Marketdemand

Marketsupply

p*

q*

An sales tax lowersthe market demandcurve by $t

$t

47


p

D(p), S(p)

Marketdemand

Marketsupply

p*

q*

An sales tax lowersthe market demandcurve by $t, lowersthe sellers’ price andreduces the quantitytraded.$t

qt

ps

48


p

D(p), S(p)

Marketdemand

Marketsupply

p*

q*

An sales tax lowersthe market demandcurve by $t, lowersthe sellers’ price andreduces the quantitytraded.$t

pbpb

qt

pb

And buyers pay pb = ps + t.

ps

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p

D(p), S(p)

Marketdemand

Marketsupply

p*

q*

A sales tax levied atrate $t has the sameeffects on themarket’s equilibriumas does an supplier taxlevied at rate $t.$t

pbpb

qt

pb

ps

$t

50

Pérdida irrecuperable = $90 millones

O + impuesto

Por qué no se grava el jugo de naranja

Cantidad (millones de litros al día)

Prec

io (

cent

avos

por

litr

o)

60

0 200 300 400 500100

O

D

130

40

Impuesto = $0.90 por litro

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Eficiencia de la competencia perfecta La competencia perfecta permite el uso

eficiente de los recursos si no hay beneficios externos ni costos externos

Hay tres principales obstáculos a la eficiencia:

1. Monopolio

2. Bienes públicos

3. Externalidades positivas o negativas

1 Entrada y salida Puntos sobresalientes 1. A medida que entran nuevas empresas a la industria, el...

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