Cobb-Douglas
Production
Function

Pasakorn S. 5520212001
Nabduan D. 5520212002
Ata K. 552022009
What is Cobb-Douglas Production
Function?
During 1900–1947, Charles Cobb and Paul
Douglas formulated and tested the Cobb–
Douglas production function through various
statistical evidence.

Q = b0 X Y
b1

b2

The Cobb–Douglas functional form of
production functions is widely used to represent
the relationship of an output and two inputs.
Question 7.2
Production Function Estimation. WashingtonPacific, Inc., manufactures and sells lumber,
plywood, veneer, particle board, medium-density
fiber board, and laminated beams. The company
has estimated the following multiplicative
production function for basic lumber products in
the Pacific Northwest market:

Q = b0 L K E
b1

b2

b3

Q = output,
L = labor input in worker hours,
K = capital input in machine hours and
E = energy input in BTUs (British Thermal Unit)
Each of the parameters of this model
was estimated by regression analysis
using monthly data over a 3-years
period. Coefficient estimation results
were as follows:

ˆ
ˆ
ˆ
ˆ
b0 = 0.9; b1 = 0.4; b2 = 0.4; b3 = 0.2
The standard error estimates for each
coefficient are

σ b 0 = 0.6; σ b1 = 0.1; σ b 2 = 0.2; σ b 3 = 0.1
Question 1. Estimate the effect on
output of a 1% decline in worker hours
(holding K and E constant)
Given,

Q = b0 L K E
b1

b2

b3

Take the first derivation with respect to
worker hours (L)

Q = 0L K
b
b1

b2

E

b3
∂
Q
1
=b0b1 Lb1 − K b2 E b3
∂
L
∂
Q
1
=b1b0 Lb1 K b2 E b3 L−
∂
L
∂
Q
1
=b1QL−
∂
L
∂
Q
Q
∂
Q
∂
L
=b1
=b1 *
Q
L
∂
L
L
∂
Q
∂
Q L
= 0.4( − .01)
0
*
=b1
Q
∂
L Q
∂
Q
= − .004 = − .4%
0
0
∂
Q ∂
L
Q
b1 =
÷
Q
L
Question 2 . Estimate the effect on output
of a 5% reduction in machine hours
availability accompanied by a 5% decline in
energy input (holding L constant)
Solution: From part A it is clear that,

∂Q
= b2 (∆K / K ) + b3 (∆E / E )
Q
∂Q
= 0.4(−0.05) + 0.2(−0.05)
Q
∂Q
= −0.03 = −3%
Q

ˆ
b0 = 0.9
ˆ
b = 0 .4
1

ˆ
b2 = 0.4
ˆ
b3 = 0.2
Question 3. Estimate the returns to scale for
this production system.
Solution:
In case of Cobb Douglas production function,
the returns to scale are determined by
summing up exponents because:

Q =b0 L K
b1

b2

E

b3

hQ =b0 ( kL) ( kK )
b1

b2

hQ =k

b1 + 2 + 3
b
b

b0 L K

hQ =k

b1 + 2 + 3
b
b

Q

b1

( kE )

b2

E

b3

b3
Thus, summing up the value of the
exponents, we get,

b1 + b2 + b3 = 0.4 + 0.4 + 0.2 = 1
hQ = k Q
1

h=k

1

This indicates constant returns to
scale estimation.
Graph
hQ = kn.f(X.Y.Z)
Constant
n=1 h=k
Increasing
n>1 h>k
decreasing
n<1 h<k
returns-to-scale
estimation
Conclusion
Returns

to Scale is the quantitative change
in output of a firm or industry resulting from
a proportionate increase in all inputs.
Adding

the value of the exponents, we can
determine the returns to scale of a
production function.
Thank You

Cobb-Douglas Production Function

  • 1.
  • 2.
    What is Cobb-DouglasProduction Function? During 1900–1947, Charles Cobb and Paul Douglas formulated and tested the Cobb– Douglas production function through various statistical evidence. Q = b0 X Y b1 b2 The Cobb–Douglas functional form of production functions is widely used to represent the relationship of an output and two inputs.
  • 3.
    Question 7.2 Production FunctionEstimation. WashingtonPacific, Inc., manufactures and sells lumber, plywood, veneer, particle board, medium-density fiber board, and laminated beams. The company has estimated the following multiplicative production function for basic lumber products in the Pacific Northwest market: Q = b0 L K E b1 b2 b3 Q = output, L = labor input in worker hours, K = capital input in machine hours and E = energy input in BTUs (British Thermal Unit)
  • 4.
    Each of theparameters of this model was estimated by regression analysis using monthly data over a 3-years period. Coefficient estimation results were as follows: ˆ ˆ ˆ ˆ b0 = 0.9; b1 = 0.4; b2 = 0.4; b3 = 0.2 The standard error estimates for each coefficient are σ b 0 = 0.6; σ b1 = 0.1; σ b 2 = 0.2; σ b 3 = 0.1
  • 5.
    Question 1. Estimatethe effect on output of a 1% decline in worker hours (holding K and E constant) Given, Q = b0 L K E b1 b2 b3 Take the first derivation with respect to worker hours (L) Q = 0L K b b1 b2 E b3
  • 6.
    ∂ Q 1 =b0b1 Lb1 −K b2 E b3 ∂ L ∂ Q 1 =b1b0 Lb1 K b2 E b3 L− ∂ L ∂ Q 1 =b1QL− ∂ L ∂ Q Q ∂ Q ∂ L =b1 =b1 * Q L ∂ L L ∂ Q ∂ Q L = 0.4( − .01) 0 * =b1 Q ∂ L Q ∂ Q = − .004 = − .4% 0 0 ∂ Q ∂ L Q b1 = ÷ Q L
  • 7.
    Question 2 .Estimate the effect on output of a 5% reduction in machine hours availability accompanied by a 5% decline in energy input (holding L constant) Solution: From part A it is clear that, ∂Q = b2 (∆K / K ) + b3 (∆E / E ) Q ∂Q = 0.4(−0.05) + 0.2(−0.05) Q ∂Q = −0.03 = −3% Q ˆ b0 = 0.9 ˆ b = 0 .4 1 ˆ b2 = 0.4 ˆ b3 = 0.2
  • 8.
    Question 3. Estimatethe returns to scale for this production system. Solution: In case of Cobb Douglas production function, the returns to scale are determined by summing up exponents because: Q =b0 L K b1 b2 E b3 hQ =b0 ( kL) ( kK ) b1 b2 hQ =k b1 + 2 + 3 b b b0 L K hQ =k b1 + 2 + 3 b b Q b1 ( kE ) b2 E b3 b3
  • 9.
    Thus, summing upthe value of the exponents, we get, b1 + b2 + b3 = 0.4 + 0.4 + 0.2 = 1 hQ = k Q 1 h=k 1 This indicates constant returns to scale estimation.
  • 10.
    Graph hQ = kn.f(X.Y.Z) Constant n=1h=k Increasing n>1 h>k decreasing n<1 h<k returns-to-scale estimation
  • 11.
    Conclusion Returns to Scale isthe quantitative change in output of a firm or industry resulting from a proportionate increase in all inputs. Adding the value of the exponents, we can determine the returns to scale of a production function.
  • 12.