清华大学中级微观经济学讲义16课件

p
Market demand
Market supply
Change to buyers’
pb
$t
price is pb - p*.
p*
Change to quantity
ps
demanded is Dq.
qt q* Dq
D(p), S(p)
Tax Incidence and Own-Price Elasticities
pb
buyers
p* ps
Tax paid by sellers
qt q*
D(p), S(p)
Quantity Taxes & Market Equilibrium
E.g. suppose the market demand and supply curves are linear. D (p b ) a b p b
qt D(pb)S(ps) abpbadbbcd bdt.
Quantity Taxes & Market Equilibrium
psabcdbt pbabcddt
qtadbcbdt bd
As t increases, and
ps falls, pb rises, qt falls.
Quantity Taxes & Market Equilibrium
Quantity Taxes
p bp st and D (p b ) S (p s ) describe the market’s equilibrium. Notice that these two conditions apply no matter if the tax is levied on sellers or on buyers. Hence, a sales tax rate $t has the same effect as an excise tax rate $t.
equilibrium
Market Equilibrium
A market is in equilibrium when total quantity demanded by buyers equals total quantity supplied by sellers.
Market Equilibrium
How are prices affected? How is the quantity traded affected? Who pays the tax? How are gains-to-trade altered?
Quantity Taxes
A tax rate t makes the price paid by buyers, pb, higher by t from the price received by sellers, ps. p bp st
raises the buyers’
price and lowers the
quantity traded.
qt q*
D(p), S(p)
Quantity Taxes & Market Equilibrium
p
Market demand
pb p* ps
Market
supply An excise tax
p
Market demand
p*
Market supply
q=S(p)
D(p*) = S(p*); the market is in equilibrium.
q=D(p)
q*
D(p), S(p)
Market Equilibrium
Two special cases: quantity supplied is fixed, independent of the market price, and quantity supplied is extremely sensitive to the market price.
T tq tta d b c b d t. b d
Tax Incidence and Own-Price
Elasticities
p
Market demand
Market supply
pb
$t
p*
ps
qt q*
D(p), S(p)
Tax Incidence and Own-Price
Elasticities
raises the market
$t
supply curve by $t
q*
D(p), S(p)
Quantity Taxes & Market Equilibrium
p
Market demand
pb p*
Market
supply An excise tax
raises the market
$t
supply curve by $t,
S (p s ) c d p s
Quantity Taxes & Market Equilibrium
D (p b ) a b p b and S ( p s ) c d p s . With the tax, the market equilibrium satisfies
p bp st and D (p b ) S (p s )so p bp st and a b p b c d p s .
Change to sellers’
pb
$t
price is ps - p*.
p*
Change to quantity
http://www.sem.tsinghua.edu.cn/ Chapter Sixteen
Equilibrium
What Do We Do in This Chapter?
We study the concept of equilibrium We will study external changes to
supply An sales tax lowers
the market demand
curve by $t, lowers
the sellers’ price and
reduces the quantity
$t
traded.
qt q*
D(p), S(p)
Quantity Taxes & Market Equilibrium
Around p = p* the own-price elasticity of demand is approximately
Dq
Dpbq*p*
p*
pbp*DD qpq**.
Tax Incidence and Own-Price
Elasticities
p
Market demand
Market supply
psabcdbt pbabcddt
qtadbcbdt bd
The tax paid per unit by the buyer is
p b p * a b c d d t b a c d b d t d .
The tax paid per unit by the seller is
D (p b ) S (p s )
Quantity Taxes
p bp st and D (p b ) S (p s ) describe the market’s equilibrium. Notice these conditions apply no matter if the tax is levied on sellers or on buyers.
Market Equilibrium
p
Market demand
Market quantity supplied is fixed, independent of price.
S(p) = c+dp, so d=0 and S(p) c.
q* = c
D-1(q) = (a-q)/b q
Market Equilibrium
p
Market demand
Market quantity supplied is
extremely sensitive to price. S-1(q) = p*.
p* D-1(q) = (a-q)/b q
Quantity Taxes
A quantity tax levied at a rate of $t is a tax of $t paid on each unit traded.
Quantity Taxes & Market Equilibrium
p
Market demand
Market supply
No tax
p*
q*
D(p), S(p)
Quantity Taxes & Market Equilibrium
p
Market demand
p*
Market
supply An excise tax
Substituting for pb gives
a b ( p s t ) c d p s p s a b c d b t .
Quantity Taxes & Market Equilibrium
psabcdbt and
pbabcddt
p bp st give
The quantity traded at equilibrium is
And buyers pay pb = ps + t.
Quantity Taxes & Market Equilibrium
Who pays the tax of $t per unit traded?
The division of the $t between buyers and sellers is the incidence of the tax.
p
Market demand
p*
Market supply
An sales tax lowers the market demand curve by $t
$t
q*
D(p), S(p)
Quantity Taxes & Market Equilibrium
p
Market demand
p* ps
Market
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.
p * p s b a c d a b c d b t b b t d .
Quantity Taxes & Market Equilibrium
psabcdbt pbabcddt
qtadbcbdt bd
The total tax paid (by buyers and sellers combined) is
Quantity Taxes & Market Equilibrium
p
Market demand
Market supply
pb p* ps
qt q*
D(p), S(p)
Quantity Taxes & Market Equilibrium
p
Market demand
Market supply
Tax paid by
If the tax is levied on sellers then it is an excise tax.
If the tax is levied on buyers then it is a sales tax.
Quantity Taxes
What is the effect of a quantity tax on a market’s equilibrium?
raises the market
$t
supply curve by $t,
raises the buyers’
price and lowers the
quantity traded.
qt q*
Dwk.baidu.comp), S(p)
And sellers receive only ps = pb - t.
Quantity Taxes & Market Equilibrium
p
Market demand
pb p* ps
Market
supply An sales tax lowers
the market demand
curve by $t, lowers
the sellers’ price and
reduces the quantity
$t
traded.
qt q*
D(p), S(p)