Chapter 14 Perfect Competition
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Transcript of Chapter 14 Perfect Competition
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Chapter 14Perfect Competition
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The Meaning of Competition A perfectly competitive market has
the following characteristics:– Many buyers and sellers– Homogenous good– Free entry and exit
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The Meaning of Competition As a result of its characteristics, the
perfectly competitive market has the following outcomes:– The actions of any single buyer or seller
in the market have a negligible impact on the market price.
– Each buyer and seller takes the market price as given.
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The Competitive Firm’s supply
The goal of a competitive firm is to maximize profit.
This means that the firm will want to produce the quantity that maximizes the difference between total revenue and total cost.
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The Revenue of a Competitive Firm
Average revenue is how much revenue a firm receives for the typical unit sold. In a perfect competitive market average revenue equals the price of the good.A v erag e R e ven u e = T o ta l rev en u e
Q uan tity
P rice Q uan tityQ uan tity
P rice
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The Revenue of a Competitive Firm
Marginal revenue is the change in total revenue from an additional unit sold.
MR =TR/Q For competitive firms, marginal
revenue equals the price of the good.
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Total, Average, and Marginal Revenue for a Competitive
Firm
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Profit Maximization
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Profit Maximization
Quantity0
Costsand
Revenue
TR
TR 1
Q 1
If the firm produces Q1, profit is maximized.
If the firm produces Q2, profit=0.
TC 1
TC
Q2
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Profit Maximization: MR=MC
Profit maximization occurs at the quantity where marginal revenue equals marginal cost.– When MR > MC, increasing Q raises
profit– When MR < MC, decreasing Q raises
profit– When MR = MC, profit is maximized.
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Profit Maximization
Quantity0
Costsand
RevenueMC
ATC
AVC
MC1
Q1
MC2
Q2
The firm maximizesprofit by producing the quantity at whichmarginal cost equalsmarginal revenue.
QMAX
P = MR1 = MR2 P = AR = MR
If the firm produces Q1, marginal cost is MC1.
If the firm produces Q2, marginal cost is MC2.
Suppose the market price is P.
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Marginal Cost as the Supply Curve
Quantity0
Price
MC
ATC
AVCP1
Q1
P2
Q2
So, this section of thefirm’s MC curve isalso the firm’s supplycurve.
As P increases, the firm will select its level of output along the MC curve.
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Firm making losses: not shut down
Quantity0
Costsand
Revenue
TR
TC 1
Q 1
The firm realizes minimum losses at Q1.
Total cost is always higher than total revenue.
TR 1
TC
MR=MC gives the optimum production point
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Firm realizing losses: shut down
Quantity0
Costsand
Revenue
TR
TC 1
Q 1
The loss at MR=MC is not the minimum.
TR 1
TCMR=MC does not always give the optimum production point
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Is MR=MC enough? MR=MC gives the optimum output
level, if the firm is to produce any output level greater than zero.
Sometimes a firm makes losses at the quantity where MR=MC.
The question then is:– Should the firm stay in business or shut
down?
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The Shut down DecisionShould a firm continue to produce
when it is realizing losses? A shutdown refers to a short-run
decision not to produce anything during a specific period of time because of current market conditions.
Exit refers to a long-run decision to leave the market.
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More Formally, Fixed costs are sunk costs The firm shuts down if the revenue is
less than the variable cost of production.
Shut down if : – Profit if in business <Profit if shut down
TR-VC-FC < 0-FCTR<VC
Divide both sides by Q:TR/Q < VC/Q
Shut down if P < AVC
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Short-Run Supply Curve
Quantity
AVC
0
Costs
If P > AVC, firm will continue to produce in the short run.
P
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Short-Run Supply Curve
Quantity
AVC
0
Costs
If P < AVC, firm will shut down.
P
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Short-Run Supply CurveMC
Quantity
ATC
AVC
0
Costs
Firmshutsdown ifP< AVC
Firm’s short-runsupply curve
If P > AVC, firm will continue to produce in the short run.
If P > ATC, the firm will continue to produce at a profit.
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The Firm’s Short-Run Decision to Shut Down
The portion of the marginal-cost curve that lies above average variable cost is the competitive firm’s short-run supply curve.
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Summary To find the profit maximizing
quantity:– Compare P and MC
To check shut down– Compare P and AVC
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Long-Run Decision to Exit or Enter a Market
In the long run, the firm exits if the revenue it would get from producing is less than its total cost, i.e. if– Profit in business <Profit if exit
TR-TC < 0 TR<TC
Divide both sides by Q: TR/Q < TC/Q
Exit if P < ATC
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Long-Run Supply Curve
MC = long-run S
Firmexits ifP < ATC
Quantity
ATC
0
CostsFirm’s long-runsupply curve
Firmenters ifP > ATC
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Summary: The Supply Curve
Short-Run Supply Curve– The portion of its marginal cost curve
that lies above average variable cost. Long-Run Supply Curve
– The marginal cost curve above the minimum point of its average total cost curve.
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Short-Run Market Supply(a) Individual Firm Supply
Quantity (firm)0
Price
MC
1.00
100
$2.00
200
(b) Market Supply
Quantity (market)0
Price
Supply
1.00
100,000
$2.00
200,000
If the industry has 1000 identical firms, then at each market price, industry output will be 1000 times larger than the representative firm’s output.
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The Long Run and Firm Profit
When a perfect competitive industry realizes profit , entry by new firms occurs.
When a perfect competitive industry realizes losses, firms within the industry exit the market.
Firms will enter or exit the market until profits are driven to zero.
In the long run, price equals the minimum of average total cost.
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Positive profit creates entry(a) A Firm with Profits
Quantity0
Price
P = AR = MR
ATCMC
P
Q(profit-maximizing quantity)
Profit
RevenueTotal Cost
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Negative profit creates exit(b) A Firm with Losses
Quantity0
Price
ATCMC
(loss-minimizing quantity)
P = AR = MRP
ATC
Q
Loss
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Long Run Equilibrium The conditions characterizing the
long run equilibrium P and Q: – The total quantity demanded equals the
total quantity suppliedQuantity Demanded=Quantity Supplied
– Each firm maximizes profit.Price=Marginal cost
– No entry or Exit, i.e., zero profitPrice=Average total cost
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Long-Run Market Supply
(a) Firm’s Zero-Profit Condition
Quantity (firm)0
Price
(b) Market Supply
Quantity (market)
Price
0
MC
ATC
D
S
q Q
P*
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Describe the Long Run Equilibrium
firms that remain must be making zero economic profit.
Firms produce at the lowest possible unit cost, i.e. firms are operating at their efficient scale.
(a) Firm’s Zero-Profit Condition
Quantity (firm)0
Price
MC
ATC
P*
Q*
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Why Do Competitive Firms Stay in Business If they
Make Zero Profit? In the zero-profit equilibrium, the
firm’s revenue compensates the owners for the time and money they expend to keep the business going.
Total cost includes all the opportunity costs of the firm.
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Comparative Statics: A Shift in Demand in the Short Run
and Long Run An increase in demand raises price
and quantity in the short run. Firms earn profits because price now
exceeds average total cost.
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An Increase in Demand in the Short Run and Long Run
Firm(a) Initial Condition
Quantity (firm)0
Price
Market
Quantity (market)
Price
0
DDemand, 1
SShort-run supply, 1
P1
ATC
P1
1Q
A
MC
A market begins in long run equilibrium.
And firms earn zero profit.
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An Increase in Demand in the Short Run and Long Run
Market Firm(b) Short-Run Response
Quantity (firm)0
Price
P1
Quantity (market)
Long-runsupply
Price
0
D1
D2
P1
S1
P2
Q1
A
Q2
P2B
ATCMC
An increase in market demand……raises price and output.
The higher P encourages firms to produce more… …and generates short-run profit.
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An Increase in Demand in the Short Run and Long Run
P1
Firm(c) Long-Run Response
Quantity (firm)0
Price
MC ATC
Market
Quantity (market)
Price
0
P1
P2
Q1 Q2
B
D1
D2
S1
AS2
Q3
C
Profits induce entry and market supply increases.
The increase in supply lowers market price. In the long run market price is restored, but market supply is greater.
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Quantity0
P
MC
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Firm
Quantity (firm)0
PriceMarket
Quantity (market)
Price
0
D
SMC