08
Pure Competition in the Short
Run
McGraw-Hill/Irwin
Copyright © 2012 by The McGraw-Hill Companies, Inc. All rights reserved.
Four Market Models
• Pure competition
• Pure monopoly
• Monopolistic competition
• Oligopoly
Pure
Competition
Monopolistic
Competition
Oligopoly
Pure
Monopoly
Market Structure Continuum
LO1
8-2
Four Market Models
Characteristics of the Four Basic Market Models
Pure
Characteristic Competition
Monopolistic
Competition
Oligopoly
Monopoly
Number of firms
A very large
number
Many
Few
One
Type of product
Standardized
Differentiated
Standardized or
differentiated
Unique; no
close subs.
Control over
price
None
Some, but within rather
narrow limits
Limited by mutual
inter-dependence;
considerable with
collusion
Considerable
Conditions of
entry
Very easy, no
obstacles
Relatively easy
Significant
obstacles
Blocked
Nonprice
Competition
None
Considerable emphasis
on advertising, brand
names, trademarks
Typically a great
deal, particularly
with product
differentiation
Mostly public
relation
advertising
Examples
Agriculture
Retail trade, dresses,
shoes
Steel, auto, farm
implements
Local utilities
LO1
8-3
Pure Competition: Characteristics
• Very large numbers of sellers
• Standardized product
• “Price takers”
• Easy entry and exit
• Perfectly elastic demand
• Firm produces as much or little as
they want at the price
• Demand graphs as horizontal line
LO2
8-4
Average, Total, and Marginal Revenue
• Average Revenue
• Revenue per unit
• AR = TR/Q = P
• Total Revenue
• TR = P X Q
• Marginal Revenue
• Extra revenue from 1 more unit
• MR = ΔTR/ΔQ
LO3
8-5
Average, Total, and Marginal Revenue
Firm’s
Demand
Schedule
(Average
Revenue)
P
QD
Firm’s
Revenue
Data
TR
MR
0 $131
$0
] $131
1 131 131
] 131
2 131 262
] 131
3 131 393
] 131
4 131 524
] 131
5 131 655
] 131
6 131 786
] 131
7 131 917
] 131
8 131 1048
] 131
9 131 1179
131
10 131 1310 ]
LO3
TR
D = MR = AR
8-6
Profit Maximization: TR-TC Approach
• Three questions:
• Should the firm produce?
• If so, what amount?
• What economic profit (loss) will be
realized?
LO3
8-7
Profit Maximization: TR-TC Approach
The Profit-Maximizing Output for a Purely Competitive Firm: Total Revenue –
Total Cost Approach (Price = $131)
(1)
Total Product
(Output) (Q)
(2)
Total Fixed Cost
(TFC)
(3)
Total Variable
Costs (TVC)
(4)
Total Cost
(TC)
(5)
Total Revenue
(TR)
(6)
Profit (+)
or Loss (-)
0
$100
$0
$100
$0
$-100
1
100
90
190
131
-59
2
100
170
270
262
-8
3
100
240
340
393
+53
4
100
300
400
524
+124
5
100
370
470
655
+185
6
100
450
550
786
+236
7
100
540
640
917
+277
8
100
650
750
1048
+298
9
100
780
880
1179
+299
10
100
930
1030
1310
+280
LO3
8-8
Profit Maximization: TR–TC Approach
Total Economic
Profit
Total Revenue and Total Cost
$1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
LO3
Break-Even Point
(Normal Profit)
Total Revenue, (TR)
Maximum
Economic
Profit
$299
Total Cost,
(TC)
P=$131
Break-Even Point
(Normal Profit)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Quantity Demanded (Sold)
$500
400
300
200
100
Total Economic
Profit
$299
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Quantity Demanded (Sold)
8-9
Profit Maximization: MR-MC Approach
The Profit-Maximizing Output for a Purely Competitive Firm: Marginal
Revenue – Marginal Cost Approach (Price = $131)
(1)
Total
Product
(Output)
(2)
Average
Fixed Cost
(AFC)
(3)
Average
Variable
Costs (AVC)
(4)
Average
Total Cost
(ATC)
(5)
Marginal
Cost
(MC)
(5)
Price =
Marginal
Revenue
(MR)
0
LO3
(6)
Total
Economic
Profit (+)
or Loss (-)
$-100
1
$100.00
$90.00
$190
$90
$131
-59
2
50.00
85.00
135
80
131
-8
3
33.33
80.00
113.33
70
131
+53
4
25.00
75.00
100.00
60
131
+124
5
20.00
74.00
94.00
70
131
+185
6
16.67
75.00
91.67
80
131
+236
7
14.29
77.14
91.43
90
131
+277
8
12.50
81.25
93.75
110
131
+298
9
11.11
86.67
97.78
130
131
+299
10
10.00
93.00
103.00
150
131
+280
8-10
Profit Maximization: MR-MC Approach
Cost and Revenue
$200
MR = MC
150
MC
P=$131
MR = P
ATC
Economic Profit
100
AVC
A=$97.78
50
0
1
2
3
4
5
6
7
8
9
10
Output
LO3
8-11
Loss-Minimizing Case
• Loss minimization
• Still produce because P > minAVC
• Losses at a minimum where
MR=MC
LO3
8-12
Loss-Minimizing Case
Cost and Revenue
$200
MC
150
Loss
A=$91.67
ATC
AVC
100
P=$81
50
0
MR = P
V = $75
1
2
3
4
5
6
7
8
9
10
Output
LO3
8-13
Shutdown Case
Cost and Revenue
$200
MC
150
ATC
V = $74
100
AVC
MR = P
P=$71
Short-Run Shut Down Point
P < Minimum AVC
$71 < $74
50
0
1
2
3
4
5
6
7
8
9
10
Output
LO3
8-14
Marginal Cost and Short-Run Supply
The Supply Schedule of a Competitive Firm Confronted with the Cost
Data in the table in Figure 8.3
LO4
Price
Quantity
Supplied
Maximum Profit (+)
Minimum Loss (-)
$151
10
$+480
131
9
+299
111
8
+138
91
7
-3
81
6
-64
71
0
-100
61
0
-100
8-15
Cost and Revenues (Dollars)
Marginal Cost and Short-Run Supply
e
P5
P3
P2
P1
0
MR5
d
P4
ATC
c
AVC
b
a
Q2
Q3
MC
Q4
MR4
MR3
MR2
MR1
Q5
Quantity Supplied
LO4
8-16
Cost and Revenues (Dollars)
Marginal Cost and Short-Run Supply
S
e
P5
P3
P2
P1
MR5
d
P4
MC
ATC
c
AVC
b
a
MR4
MR3
MR2
MR1
Shut-Down Point
(If P is Below)
0
Q2
Q3
Q4
Q5
Quantity Supplied
LO4
8-17
3 Production Questions
Output Determination in Pure Competition in the Short Run
LO3
Question
Answer
Should this firm produce?
Yes, if price is equal to, or greater than,
minimum average variable cost. This
means that the firm is profitable or that
its losses are less than its fixed cost.
What quantity should this firm produce?
Produce where MR (=P) = MC; there,
profit is maximized (TR exceeds TC by
a maximum amount) or loss is
minimized.
Will production result in economic
profit?
Yes, if price exceeds average total cost
(TR will exceed TC). No, if average
total cost exceeds price (TC will exceed
TR).
8-18
Firm and Industry: Equilibrium
Firm and Market Supply and the Market Demand
LO4
(1)
Quantity
Supplied,
Single
Firm
(2)
Total
Quantity
Supplied,
1000 Firms
(3)
Product
Price
(4)
Total
Quantity
Demanded
10
10,000
$151
4,000
9
9,000
131
6,000
8
8,000
111
8,000
7
7,000
91
9,000
6
6,000
81
11,000
0
0
71
13,000
0
0
61
16,000
8-19
Firm and Industry: Equilibrium
S = ∑ MC’s
s = MC
Economic
Profit
ATC
d
$111
$111
AVC
D
8
LO4
8000
8-20
Fixed Costs: Digging Out of a Hole
• Shutting down in the short run does
•
•
•
not mean shutting down forever
Low prices can be temporary
Some firms switch production on and
off depending on the market price
Examples: oil producers, resorts, and
firms that shut down during a
recession
8-21