Firm Supply:
Market Structure & Perfect
Competition
Firm Supply
How does a firm decide how much to
supply at a given price? This
depends upon the firm’s
– goals;
– technology...
Market Environment
Are there many other firms?
How do other firms’ decisions effect
the firm’s payoffs?
Market Environment
Monopoly: Just one seller that
determines the quantity supplied/the
market-clearing price.
Oligopoly: A...
Market Environment
Dominant Firm: Many firms, but one
much larger than the rest. The large
firm’s decisions affect the pay...
Market Environment
Monopolistic Competition: Many
firms each making a slightly different
product. Each firm’s output level...
Perfect Competition
Assumptions
There are many buyers and sellers,
– each firm is a price-taker
Homogeneous product
Freedo...
Perfect Competition
What is the demand curve faced by
the firm?
Perfect Competition

P

Market Supply

pe
Market Demand

Q
Perfect Competition
P
Market Supply

p’
pe

At a price of p’, zero is
demanded from the firm.
Market Demand

Q
Perfect Competition

P

Market Supply

p’
pe
p”

At a price of p’, zero is
demanded from the firm.
Market Demand

Q
At a p...
Perfect Competition
Therefore, the demand curve faced
by the individual firm is ...
Perfect Competition
P

Market
Supply

P

P*

P*
Market
Demand
Q

y
Firm’s Demand Curve
The Firm’s Short-Run Supply
Decision?
Each firm is a profit-maximizer
Each firm choose its output level by
solving

maxΠ (...
The Firm’s Short-Run Supply
Decision?
maxΠ ( y ) = py − c( y )
y≥0

What does the solution ys* look like?
The Firm’s Short-Run Supply
Decision?
maxΠ( y ) = py − c( y )
y ≥0

F.O.C.

Π(y)

S.O.C.

ys*

dΠ ( y )
(i )
= p − MC s ( ...
The Firm’s Short-Run Supply
Decision?

The first-order maximum profit condition
is
dΠ ( y )
= p − MC ( y ) = 0
dy
That is,...
The Firm’s Short-Run Supply
Decision?
P

pe
MCs(y)
y’

ys*

At y = ys*,
p = MC
and MC
slopes
upwards,
y = ys* is
profity m...
P

The Firm’s Short-Run Supply
Decision?

pe
MCs(y)
y’

ys*

At y = y’, p =
MC and MC
slopes
downwards,
y = y’ is
profitmi...
P

The Firm’s Short-Run Supply
Decision?

pe
MCs(y)
y’

ys*

So a profitmaximising
supply level
can lie only
on the
upward...
The Firm’s Short-Run Supply
Decision?
But not every point on the upwardsloping part of the firm’s MC curve
represents a pr...
The Firm’s Short-Run Supply
Decision?
The firm will not supply any output if

p < AVC ( y )
Shut Down Point: P = AVC(y)
The Firm’s Short-Run Supply
Decision?

P

MCs(y)
ACs(y)
AVCs(y)

y
The Firm’s Short-Run Supply
Decision?

P

MCs(y)
ACs(y)
AVCs(y)

y
The Firm’s Short-Run Supply
Decision?

P

MCs(y)
ACs(y)
AVCs(y)
The firm’s short-run
supply curve
y
p > AVCs(y)
The Firm’s Short-Run Supply
Decision?

P

Shutdown
MCs(y)
point
ACs(y)

AVCs(y)
The firm’s short-run
supply curve
y
Short Run Market Supply Curve
P
S

Market
Supply Curve
is the sum of
all the firms
supply
curves
(≈ΣMC)

Q
The Firm’s Long-Run Supply
Decision?
The long-run is the circumstance in
which the firm can choose amongst
all of its shor...
The Firm’s Long-Run Supply
Decision?
A competitive firm’s long-run profit
function is

Π( y ) = py − c( y )

The long-run ...
The Firm’s Long-Run Supply
Decision?
The firm’s long-run supply level
decision is to maximise,

Π( y ) = py − c( y )
The Firm’s Long-Run Supply
Decision?
Additionally, the firm’s economic
profit level must not be negative,
since the firm w...
The Firm’s Long-Run Supply
Decision?
P

MC(y)

AC(y)

y
The Firm’s Long-Run Supply
Decision?
P

MC(y)

p > AC(y)
AC(y)

y
P

The Firm’s Long-Run Supply
Decision?
The firm’s long-run
supply curve

MC(y)

AC(y)

y
Application: Tax Incidence In
Perfect Competition
Market
Supply

P
PC = PP

Q
No tax: PC = PP

Market
Demand
Application: Tax Incidence In
Perfect Competition
P

Market
Supply

PC

PP

A tax is introduced.

Market
Demand
Q

This is...
Application: Tax Incidence In
Perfect Competition
P

Market
Supply

PC

PP

This is
the tax.

Market
Demand
Q

The tax cre...
Application: Tax Incidence In
Perfect Competition
P

Market
Supply

PC

PP

This is
the tax

Market
Demand
Q

In the short...
Application: Tax Incidence In
Perfect Competition
In the short run,
The producers receives less for the
product.
Some firm...
Application: Tax Incidence In
Perfect Competition
In the Long Run,
Consumers pay all of the tax (100%)
Producers pay none ...
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Lecture13 copy

  1. 1. Firm Supply: Market Structure & Perfect Competition
  2. 2. Firm Supply How does a firm decide how much to supply at a given price? This depends upon the firm’s – goals; – technology; – market environment; and – competitors’ behaviour.
  3. 3. Market Environment Are there many other firms? How do other firms’ decisions effect the firm’s payoffs?
  4. 4. Market Environment Monopoly: Just one seller that determines the quantity supplied/the market-clearing price. Oligopoly: A very small number of firms, the decision of each influencing the payoffs of the other firms.
  5. 5. Market Environment Dominant Firm: Many firms, but one much larger than the rest. The large firm’s decisions affect the payoffs of each small firm. Decisions by any one small firm do not noticeably effect the payoffs of any other firm.
  6. 6. Market Environment Monopolistic Competition: Many firms each making a slightly different product. Each firm’s output level is small relative to the total. Perfect Competition: Many firms, all making the same product. Each firm’s output level is very small relative to the total output level.
  7. 7. Perfect Competition Assumptions There are many buyers and sellers, – each firm is a price-taker Homogeneous product Freedom of entry and exit Perfect information
  8. 8. Perfect Competition What is the demand curve faced by the firm?
  9. 9. Perfect Competition P Market Supply pe Market Demand Q
  10. 10. Perfect Competition P Market Supply p’ pe At a price of p’, zero is demanded from the firm. Market Demand Q
  11. 11. Perfect Competition P Market Supply p’ pe p” At a price of p’, zero is demanded from the firm. Market Demand Q At a price of p” the firm faces the entire market demand.
  12. 12. Perfect Competition Therefore, the demand curve faced by the individual firm is ...
  13. 13. Perfect Competition P Market Supply P P* P* Market Demand Q y Firm’s Demand Curve
  14. 14. The Firm’s Short-Run Supply Decision? Each firm is a profit-maximizer Each firm choose its output level by solving maxΠ ( y ) = py − c( y ) y≥0
  15. 15. The Firm’s Short-Run Supply Decision? maxΠ ( y ) = py − c( y ) y≥0 What does the solution ys* look like?
  16. 16. The Firm’s Short-Run Supply Decision? maxΠ( y ) = py − c( y ) y ≥0 F.O.C. Π(y) S.O.C. ys* dΠ ( y ) (i ) = p − MC s ( y ) = 0 dy ( ii ) y d 2Π ( y ) dy 2 < 0 at y = y * s
  17. 17. The Firm’s Short-Run Supply Decision? The first-order maximum profit condition is dΠ ( y ) = p − MC ( y ) = 0 dy That is, p = MC So at a profit maximum with ys* > 0, the market price p equals the marginal cost of production at y = ys*.
  18. 18. The Firm’s Short-Run Supply Decision? P pe MCs(y) y’ ys* At y = ys*, p = MC and MC slopes upwards, y = ys* is profity maximizing.
  19. 19. P The Firm’s Short-Run Supply Decision? pe MCs(y) y’ ys* At y = y’, p = MC and MC slopes downwards, y = y’ is profitminimizing. y
  20. 20. P The Firm’s Short-Run Supply Decision? pe MCs(y) y’ ys* So a profitmaximising supply level can lie only on the upwards sloping part of the firm’s y MC curve.
  21. 21. The Firm’s Short-Run Supply Decision? But not every point on the upwardsloping part of the firm’s MC curve represents a profit-maximum. The firm will choose an output level y > 0 only if p ≥ AVC ( y )
  22. 22. The Firm’s Short-Run Supply Decision? The firm will not supply any output if p < AVC ( y ) Shut Down Point: P = AVC(y)
  23. 23. The Firm’s Short-Run Supply Decision? P MCs(y) ACs(y) AVCs(y) y
  24. 24. The Firm’s Short-Run Supply Decision? P MCs(y) ACs(y) AVCs(y) y
  25. 25. The Firm’s Short-Run Supply Decision? P MCs(y) ACs(y) AVCs(y) The firm’s short-run supply curve y p > AVCs(y)
  26. 26. The Firm’s Short-Run Supply Decision? P Shutdown MCs(y) point ACs(y) AVCs(y) The firm’s short-run supply curve y
  27. 27. Short Run Market Supply Curve P S Market Supply Curve is the sum of all the firms supply curves (≈ΣMC) Q
  28. 28. The Firm’s Long-Run Supply Decision? The long-run is the circumstance in which the firm can choose amongst all of its short-run circumstances. How does the firm’s long-run supply decision compare to its short-run supply decisions?
  29. 29. The Firm’s Long-Run Supply Decision? A competitive firm’s long-run profit function is Π( y ) = py − c( y ) The long-run cost c(y) of producing y units of output consists only of variable costs since all inputs are variable in the long-run.
  30. 30. The Firm’s Long-Run Supply Decision? The firm’s long-run supply level decision is to maximise, Π( y ) = py − c( y )
  31. 31. The Firm’s Long-Run Supply Decision? Additionally, the firm’s economic profit level must not be negative, since the firm would exit the market in that case. Therefore, p ≥ ATC ( y )
  32. 32. The Firm’s Long-Run Supply Decision? P MC(y) AC(y) y
  33. 33. The Firm’s Long-Run Supply Decision? P MC(y) p > AC(y) AC(y) y
  34. 34. P The Firm’s Long-Run Supply Decision? The firm’s long-run supply curve MC(y) AC(y) y
  35. 35. Application: Tax Incidence In Perfect Competition Market Supply P PC = PP Q No tax: PC = PP Market Demand
  36. 36. Application: Tax Incidence In Perfect Competition P Market Supply PC PP A tax is introduced. Market Demand Q This is the tax.
  37. 37. Application: Tax Incidence In Perfect Competition P Market Supply PC PP This is the tax. Market Demand Q The tax creates a wedge between the price firms receive and the price consumers pays. The difference is the tax.
  38. 38. Application: Tax Incidence In Perfect Competition P Market Supply PC PP This is the tax Market Demand Q In the short run, the burden of the tax is shared (not necessarily on a 50/50 basis) between consumers and producers.
  39. 39. Application: Tax Incidence In Perfect Competition In the short run, The producers receives less for the product. Some firms will continue to produce output at a loss once they are covering their average variable costs. Some firms will experience losses and so exit the market. The supply curve shifts to the left and the prices consumers and producers face increases.
  40. 40. Application: Tax Incidence In Perfect Competition In the Long Run, Consumers pay all of the tax (100%) Producers pay none of tax (0%) There are no firms making losses

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