INTRODUCTION TO INDUSTRIAL ORGANIZATION
Program
PART 1. INTRODUCTION PART 2. OLIGOPOLY
1. Oligopoly Compe..on 2. Collusion
PART 3. PRICE AND NONPRICE STRATEGIES 1. Price Discrimina.on
2. Ver.cal Rela.ons
3. Product Differen.a.on 4. Adver.sing
PART 4. MARKET STRUCTURE 1. Entry Deterrence
2. Mergers and Acquisi.ons
PART 5. RESEARCH AND DEVELOPMENT
INTRODUCTION TO INDUSTRIAL ORGANIZATION
Program
PART 1. INTRODUCTION PART 2. OLIGOPOLY
1. Oligopoly Compe<<on 2. Collusion
PART 3. PRICE AND NONPRICE STRATEGIES 1. Price Discrimina.on
2. Ver.cal Rela.ons
3. Product Differen.a.on 4. Adver.sing
PART 4. MARKET STRUCTURE 1. Entry Deterrence
2. Mergers and Acquisi.ons
PART 5. RESEARCH AND DEVELOPMENT
Part II
Oligopoly
Chapter II.1
Oligopoly Compe..on
• Between perfect compe..on and monopoly: Oligopoly, a market with some firms.
• Both in a monopoly under perfect compe..on, nobody cares about any rival’s ac.ons or reac.ons.
• However, in an oligopoly ...
• Example (Wall Street Journal, 1999):
Coca-‐Cola wanted to increase its prices by 5% to increase its profits.
However, the result of such an acPon depends on Pepsi’s reacPon.
• Strategic interac.on between firms in an oligopoly:
Firm 1’s ac.on Firm 2’s profit Firm 2’s profit
II.1.1. The Bertrand Model
• The Bertrand Model illustrates price compe..on in an oligopoly
• The idea:
The price of a good influences the demand for this good but also the demand for subs.tutes
! Interdependence between price seZng decisions (example:
computers Compaq /Dell)
! The Bertrand Model is the easiest one to analyze such an interdependence
II.1.1. The Bertrand Model
• The model:
– 2 firms, A and B
– homogeneous good (perfect subs.tutes) – constant marginal cost, c
– linear demand
– A and B simultaneously set their price
II.1.1. The Bertrand Model
• The game:
– players: A and B
– strategies: price seZng – rule: simultaneity
– payoff: profits
II.1.1. The Bertrand Model
• Profits
= revenue – costs = P.D(P) – c.Q
* P is the decision variable* D(P) ?
II.1.1. The Bertrand Model
• The demand
€
DA(P) = DA(PA,PB) =
0 if PA > PB D(PA)
2 if PA = PB D(PA) if PA < PB
⎧
⎨ ⎪
⎩ ⎪
II.1.1. The Bertrand Model
• The demands
€
DA(P) = DA(PA,PB) =
0 if PA > PB D(PA)
2 if PA = PB D(PA) if PA < PB
⎧
⎨ ⎪
⎩ ⎪
€
DB(P) = DB(PA,PB) =
0 if PA < PB D(PB)
2 if PA = PB D(PB) if PA > PB
⎧
⎨ ⎪
⎩ ⎪
II.1.1. The Bertrand Model
• The best price seZng strategies
– For A:
– This is A’s best reply func.on or A’s reac.on func.on
€
PA*(PB) =
PM if PB > PM PB −ε if PM > PB > c
c if c > PB
⎧
⎨ ⎪
⎩ ⎪
II.1.1. The Bertrand Model
• Graphically
PA
PB 45°
II.1.1. The Bertrand Model
• Graphically
PA
PB 45°
c
c
II.1.1. The Bertrand Model
• Graphically
PA
PB 45°
c
c PM
PM
II.1.1. The Bertrand Model
• Graphically
PA
PB 45°
c
c PM
PM
II.1.1. The Bertrand Model
• Graphically
PA
PB 45°
c
c PM
PM
II.1.1. The Bertrand Model
• Graphically
PA
PB 45°
c
c PM
PM
II.1.1. The Bertrand Model
• The best price seZng strategies
– For B: by symmetry
– This is B’s best reply func.on or B’s reac.on func.on
€
PB*(PA) =
PM if PA > PM PA −ε if PM > PA > c
c if c > PA
⎧
⎨ ⎪
⎩ ⎪
II.1.1. The Bertrand Model
• Graphically, for B
PA
PB 45°
c
c PM
PM
II.1.1. The Bertrand Model
• Graphically
PA
PB 45°
c
c PM
PM
II.1.1. The Bertrand Model
• Graphically
PA
PB 45°
c
c PM
PM
€
P
A*= P
B*= c
Nash Equilibrium:
II.1.1. The Bertrand Model
• Results:
– Under the Bertrand compe..on condi.ons (price compe..on with homogeneous goods and constant
symmetric marginal costs), firms set their prices equal to marginal cost.
– No.ce that with only 2 firms, we obtain the sale outcome as under perfect compe..on
II.1.1. The Bertrand Model
• Limita.ons:
– Homogeneous goods implying demand is 0 or 1 – Sta.c framework, no possibility for retalia.on – No capacity constraint
II.1.2. Price SeZng with Capacity Constraints
• The Model
– Same as in II.1.1
– but with limited produc.on capaci.es, KA and KB – c = 0, for simplicity and wlog
II.1.2. Price SeZng with Capacity Constraints
• The Demands
If PB > PA and D(PA) > KA , then qA = KA and
€
qB =
0 if D(PB)− KA ≤ 0 D(PB)− KA if 0 ≤ D(PB)− KA ≤ KB
KB if KB ≤ D(PB)− KA
⎧
⎨ ⎪
⎩ ⎪
II.1.2. Price SeZng with Capacity Constraints
• Result
– If the total market capacity is low enough compared to the market demand, then the equilibrium price is higher than the marginal cost.
– In par.cular, P* = P( KA + KB )
KA + KB P( KA + KB )
P
Q
II.1.3 The Cournot Model The symmetric duopoly case
• The model
–
2 firms, A and B
–
homogeneous good
– c, constant marginal cost
–
the market price is unique and depends on the total produc.on
–
firms simultaneously decide their produc.on
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• For any quan.ty qB produced by firm B, firm A’s problem is similar to the problem of a monopolist that faces the following residual demand:
DA (qB) = D (Q) -‐ qB
P
Q D(Q)
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• For any quan.ty qB produced by firm B, firm A’s problem is similar to the problem of a monopolist that faces the following residual demand:
DA (qB) = D (Q) -‐ qB
P
Q D(Q)
qB
DA(qB)
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• For any quan.ty qB produced by firm B, firm A’s problem is similar to the problem of a monopolist that faces the following residual demand:
DA (qB) = D (Q) -‐ qB
P
Q D(Q)
qB
DA(qB)
MRA
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• For any quan.ty qB produced by firm B, firm A’s problem is similar to the problem of a monopolist that faces the following residual demand:
DA (qB) = D (Q) -‐ qB
P
Q D(Q)
qB qB
DA(qB)
MRA
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• For any quan.ty qB produced by firm B, firm A’s problem is similar to the problem of a monopolist that faces the following residual demand:
DA (qB) = D (Q) -‐ qB
! qA varies with qB (see graph).
P
Q D(Q)
qB qB
DA(qB)
MRA
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• For any quan.ty qB produced by firm B, firm A’s problem is similar to the problem of a monopolist that faces the following residual demand:
DA (qB) = D (Q) -‐ qB
! qA varies with qB (see graph).
P
Q D(Q)
qB qB
DA(qB)
MRA
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• The op.mal choice of qA depends on qB
! Best reply func.on or reac.on func.on:
• The form of the best reply func.on:
– nega.ve slope – extreme case:
• qB = 0, residual demand = total demand !
– other extreme case:
• qB = qC, residual demand below marginal cost !
€
qA* (qB)
€
q*A(0) = qM
€
qA* (qC)= 0
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• Firm A’s best reply func.on
qA
qB
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• Firm A’s best reply func.on
qC
qC qM
qM qA
qB
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• Firm A’s best reply func.on
€
qA*(qB)
qC
qC qM
qM qA
qB
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• Firm A’s best reply func.on
€
qA*(qB)
qC
qC qM
qM qA
qB
No.ce:
Linear demand and costs
! Linear best reply func.ons
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• Firm B’s best reply func.on, by symmetry
€
qB*(qA)
qC
qC qM
qM qA
qB
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• Market equilibrium
€
qB*(qA)
qC
qC qM
qM qA
qB
€
q*A(qB)
E
E: best reply for both firms Check the defini.on of a Nash equilibrium
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• Dynamic interpreta.on of the Cournot equilibrium
€
qB*(qA)
qC
qC qM
qM qA
qB
€
q*A(qB)
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• Dynamic interpreta.on of the Cournot equilibrium
€
qB*(qA)
qC
qC qM
qM qA
qB
€
q*A(qB)
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• Dynamic interpreta.on of the Cournot equilibrium
€
qB*(qA)
qC
qC qM
qM qA
qB
€
q*A(qB)
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• Dynamic interpreta.on of the Cournot equilibrium
€
qB*(qA)
qC
qC qM
qM qA
qB
€
q*A(qB)
E
II.1.3 The Cournot Model
Symmetric duopoly, graphically
• Comparison with EC and EM
qC
qC qM
qM qA
qB E
qM < qE < qC
II.1.3 The Cournot Model
Symmetric duopoly, analy.cally
Analy.cal deriva.on of the Cournot equilibrium
P = a – b Q Q = q
A+ q
BC(q
i) = c q
i, i = A, B.
II.1.3 The Cournot Model
Symmetric duopoly, analy.cally
• Firm A
ΠA = P(qA, qB) qA – c qA
= (a – b qA – b qB) qA – c qA
→ CPO : a – 2 b qA – b qB – c = 0
€
⇔ q
A*(q
B) ≡ q
A= a − bq
B− c
2b
II.1.3 The Cournot Model
Symmetric duopoly, analy.cally
• Firm B
ΠB = P(qA, qB) qB – c qB
= (a – b qA – b qB) qB – c qB
→ CPO : a – b qA – 2 b qB – c = 0
€
⇔ q
B*(q
A) ≡ q
B= a − bq
A− c
2b
II.1.3 The Cournot Model
Symmetric duopoly, analy.cally
• To find the Nash/Cournot equilibrium
– Either solve the system with 2 equa.ons and 2 unknowns qA and qB:
– Or use the symmetry between A and B: qA = qB
and
€
qA = a − bqA − c 2b
€
qB = a − bqA − c 2b
€
qA = a − bqB − c 2b
II.1.3 The Cournot Model
Symmetric duopoly, analy.cally
•
The solu.on
€
qAE = qBE = a − c 3b
€
QE = qAE + qBE = 2 3
a − c b
€
PE = a −bQE = a + 2c 3
€
SCE = 2 b
a − c 3
⎛
⎝ ⎜ ⎞
⎠ ⎟
2
€
DWLE = 1 2b
a − c 3
⎛
⎝ ⎜ ⎞
⎠ ⎟
2
€
ΠEA = ΠEB = 1 b
a − c 3
⎛
⎝ ⎜ ⎞
⎠ ⎟
2
II.1.3 The Cournot Model
Symmetric duopoly, analy.cally
•
Comparison with E
Cand E
M• EC
• EM
€
SCM = DWLM =
(
a − c)
28b
€
PC = c
€
QC = a − c b
€
SCE =
(
a − c)
22b
€
ΠC = DWLC = 0
€
PM = a + c 2
€
QM = a − c 2b
€
ΠM =
(
a − c)
24b
II.1.3 The Cournot Model
Symmetric duopoly, analy.cally
•
Comparison with E
Cand E
M!
€
QM < QE < QC
€
PM > PE > PC
€
ΣΠM > ΣΠE > ΣΠC
€
CSM < CSE < CSC
€
DWLM > DWLE > DWLC