Post on 24-Jan-2016
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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.
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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.
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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
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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.
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Geometría del excedente del consumidor
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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.
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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
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Market Equilibrium
A market is in equilibrium when total quantity demanded by buyers equals total quantity supplied by sellers.
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Market Equilibriump
D(p)
q=D(p)
Marketdemand
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Market Equilibriump
S(p)
Marketsupply
q=S(p)
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Market Equilibriump
D(p), S(p)
q=D(p)
Marketdemand
Marketsupply
q=S(p)
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Market Equilibriump
D(p), S(p)
q=D(p)
Marketdemand
Marketsupply
q=S(p)
p*
q*
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Market Equilibriump
D(p), S(p)
q=D(p)
Marketdemand
Marketsupply
q=S(p)
p*
q*
D(p*) = S(p*); the marketis in equilibrium.
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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’)
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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*.
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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”)
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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*.
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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( )
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Market Equilibriump
D(p), S(p)
D(p) = a-bp
Marketdemand
Marketsupply
S(p) = c+dp
p*
q*
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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*?
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Market EquilibriumD p a bp( ) S p c dp( )
At the equilibrium price p*, D(p*) = S(p*).
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Market EquilibriumD p a bp( ) S p c dp( )
At the equilibrium price p*, D(p*) = S(p*).That is, a bp c dp * *
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Market EquilibriumD p a bp( ) S p c dp( )
At the equilibrium price p*, D(p*) = S(p*).That is, a bp c dp * *
which gives pa cb d
*
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Market EquilibriumD p a bp( ) S p c dp( )
At the equilibrium price p*, D(p*) = S(p*).That is, a bp c dp * *
which gives pa cb d
*
and q D p S pad bcb d
* * *( ) ( ) .
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Market Equilibriump
D(p), S(p)
D(p) = a-bp
Marketdemand
Marketsupply
S(p) = c+dpp
a cb d
*
dbbcad
q*
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Market Equilibrium
One special case:
1. quantity supplied is fixed, independent of the market price, and
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Market EquilibriumMarket quantity supplied isfixed, independent of price.
p
qq*
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Market Equilibrium
S(p) = c+dp, so d=0and S(p) c.
p
qq* = c
Market quantity supplied isfixed, independent of price.
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Market Equilibrium
S(p) = c+dp, so d=0and S(p) c.
p
qq* = c
Marketdemand
Market quantity supplied isfixed, independent of price.
D(p) = a-bp
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Market Equilibrium
S(p) = c+dp, so d=0and S(p) c.
p
q
p*
D(p) = a-bp
Marketdemand
q* = c
Market quantity supplied isfixed, independent of price.
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Market Equilibrium
S(p) = c+dp, so d=0and S(p) c.
p
q
p* =(a-c)/b
Marketdemand
q* = c
Market quantity supplied isfixed, independent of price.
D(p) = a-bp
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Market Equilibrium
S(p) = c+dp, so d=0and S(p) c.
p
q
D(p) = a-bp
Marketdemand
q* = c
p* =(a-c)/b
Market quantity supplied isfixed, independent of price.
pa cb d
*
qad bcb d
*
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Market Equilibrium
S(p) = c+dp, so d=0and S(p) c.
p
q
Marketdemand
q* = cp
a cb d
*
qad bcb d
*
with d = 0 give
pa c
b*
q c* .
p* =(a-c)/b
Market quantity supplied isfixed, independent of price.
D(p) = a-bp
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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?
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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.
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Quantity Taxes
In general, if t is the amount of the quantity tax per unit sold, then
p p tb s
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Quantity Taxes
A value tax is a tax expressed in percentage units.
sb ptp )1(
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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( ) ( )
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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.
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Quantity Taxes & Market Equilibrium
p
D(p), S(p)
Marketdemand
Marketsupply
p*
q*
No tax
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Quantity Taxes & Market Equilibrium
p
D(p), S(p)
Marketdemand
Marketsupply
p*
q*
$t
An supplier taxraises the marketsupply curve by $t
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Quantity Taxes & Market Equilibrium
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
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Quantity Taxes & Market Equilibrium
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
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Quantity Taxes & Market Equilibrium
p
D(p), S(p)
Marketdemand
Marketsupply
p*
q*
No tax
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Quantity Taxes & Market Equilibrium
p
D(p), S(p)
Marketdemand
Marketsupply
p*
q*
An sales tax lowersthe market demandcurve by $t
$t
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Quantity Taxes & Market Equilibrium
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
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Quantity Taxes & Market Equilibrium
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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Quantity Taxes & Market Equilibrium
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
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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