Technology Technology
© 2010 W. W. Norton & Company, Inc.
Technologies Technologies
A technology is a process by which inputs are converted to an output.
inputs are converted to an output.
E.g. labor, a computer, a projector,
E.g. labor, a computer, a projector, electricity, and software are being combined to produce this lecture.
© 2010 W. W. Norton & Company, Inc. 2
Technologies Technologies
Usually several technologies will produce the same product -- a
produce the same product -- a
blackboard and chalk can be used blackboard and chalk can be used instead of a computer and a
projector.
projector.
Which technology is “best”?
Which technology is “best”?
How do we compare technologies?
How do we compare technologies?
© 2010 W. W. Norton & Company, Inc. 3
Input Bundles Input Bundles
xi denotes the amount used of input i;
i.e. the level of input i.
i
i.e. the level of input i.
An input bundle is a vector of the
An input bundle is a vector of the input levels; (x11, x22, … , xnn).
E.g. (x1, x2, x3) = (6, 0, 9××××3).
© 2010 W. W. Norton & Company, Inc. 4
Production Functions Production Functions
y denotes the output level.
The technology’s production
function states the maximum amount function states the maximum amount of output possible from an input
bundle.
y ==== f x ( , L , x ) y ==== f x ( 1 , L , x n )
© 2010 W. W. Norton & Company, Inc. 5
Production Functions Production Functions
One input, one output
y = f(x) is the production Output Level
One input, one output
production function.
y’ function.
y’
y’ = f(x’) is the maximal output level obtainable output level obtainable from x’ input units.
x’ x
Input Level
© 2010 W. W. Norton & Company, Inc. 6
Input Level
Technology Sets Technology Sets
A production plan is an input bundle and an output level; (x , … , x , y).
and an output level; (x1, … , xn, y).
A production plan is feasible if
A production plan is feasible if
y ≤≤≤≤ f x ( 1 , L , x n ) y ≤≤≤≤ f x ( 1 , L , x n )
The collection of all feasible
production plans is the technology set.
© 2010 W. W. Norton & Company, Inc. 7
Technology Sets Technology Sets
One input, one output
y = f(x) is the production Output Level
One input, one output
production function.
y’ function.
y’
y’ = f(x’) is the maximal output level obtainable y”
output level obtainable from x’ input units.
y” = f(x’) is an output level y” y” = f(x’) is an output level
that is feasible from x’
input units.
x’ x
Input Level
input units.
© 2010 W. W. Norton & Company, Inc. 8
Input Level
Technology Sets Technology Sets
The technology set is The technology set is
T ==== { ( x , , x , ) | y y ≤≤≤≤ f x ( , , x ) a n d
T x x y y f x x a n d
x x
n n
==== ≤≤≤≤
≥≥≥≥ ≥≥≥≥
{ ( , , , ) | ( , , )
, , } .
1 1
0 0
L L
x
1≥≥≥≥ 0 , K K , x
n≥≥≥≥ 0 } .
© 2010 W. W. Norton & Company, Inc. 9
Technology Sets Technology Sets
One input, one output
Output Level
One input, one output
y’
y’
The technology y”
The technology y” set
x’ x
Input Level
© 2010 W. W. Norton & Company, Inc. 10
Input Level
Technology Sets Technology Sets
One input, one output
Output Level
One input, one output
y’ Technically
efficient plans y’
The technology efficient plans
y”
The technology Technically set
y” Technically
inefficient plans
x’ x
Input Level plans
© 2010 W. W. Norton & Company, Inc. 11
Input Level
Technologies with Multiple Technologies with Multiple
Inputs
What does a technology look like when there is more than one input?
when there is more than one input?
The two input case: Input levels are
The two input case: Input levels are x11 and x22. Output level is y.
Suppose the production function is
y ==== ==== f x ( (
11, , x
22) ) ==== ==== 2 2 x
11 / 31x
1 / 322. .
© 2010 W. W. Norton & Company, Inc. 12
Technologies with Multiple Technologies with Multiple
Inputs
E.g. the maximal output level
E.g. the maximal output level possible from the input bundle (x , x ) = (1, 8) is
(x1, x2) = (1, 8) is
y ==== 2 x 1 / 3 x 1 / 3 ==== ××××2 1 1 / 3 ×××× 8 1 / 3 ==== ×××× ×××× ====2 1 2 4 . And the maximal output level
y ==== 2 x 11 / 3 x 1 / 32 ==== ××××2 1 1 / 3 ×××× 8 1 / 3 ==== ×××× ×××× ====2 1 2 4 .
And the maximal output level possible from (x1,x2) = (8,8) is possible from (x1,x2) = (8,8) is
y ==== 2 x
11 / 3x
1 / 32==== ×××× 2 8
1 / 3×××× 8
1 / 3==== ×××× ×××× ==== 2 2 2 8 .
y ==== 2 x
1x
2==== ×××× 2 8 ×××× 8 ==== ×××× ×××× ==== 2 2 2 8 .
© 2010 W. W. Norton & Company, Inc. 13
Technologies with Multiple Technologies with Multiple
Inputs
Output, y
x2 (8,1)
(8,8) x1
© 2010 W. W. Norton & Company, Inc. 14
Technologies with Multiple Technologies with Multiple
Inputs
The y output unit isoquant is the set of all input bundles that yield at most of all input bundles that yield at most the same output level y.
the same output level y.
© 2010 W. W. Norton & Company, Inc. 15
Isoquants with Two Variable Isoquants with Two Variable
Inputs
x2
y ≡ 8≡ 8≡ 8≡ 8 y ≡ 8≡ 8≡ 8≡ 8
y ≡ 4≡ 4≡ 4≡ 4 x1
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Isoquants with Two Variable Isoquants with Two Variable
Inputs
Isoquants can be graphed by adding an output level axis and displaying an output level axis and displaying each isoquant at the height of the each isoquant at the height of the isoquant’s output level.
© 2010 W. W. Norton & Company, Inc. 17
Isoquants with Two Variable Isoquants with Two Variable
Inputs
Output, y
y ≡ 8≡ 8≡ 8≡ 8
x2 y ≡ 4≡ 4≡ 4≡ 4
x1
© 2010 W. W. Norton & Company, Inc. 18
Isoquants with Two Variable Isoquants with Two Variable
Inputs
More isoquants tell us more about the technology.
the technology.
© 2010 W. W. Norton & Company, Inc. 19
Isoquants with Two Variable Isoquants with Two Variable
Inputs
x2
y ≡ 8≡ 8≡ 8≡ 8 y ≡ 8≡ 8≡ 8≡ 8
y ≡ 6≡ 6≡ 6≡ 6 y ≡ 4≡ 4≡ 4≡ 4 y ≡ 6≡ 6≡ 6≡ 6 y ≡ 2≡ 2≡ 2≡ 2 x1 y ≡ 2≡ 2≡ 2≡ 2
© 2010 W. W. Norton & Company, Inc. 20
Isoquants with Two Variable Isoquants with Two Variable
Inputs
Output, y
y ≡ 8≡ 8≡ 8≡ 8 y ≡ 6≡ 6≡ 6≡ 6
x2 y ≡ 4≡ 4≡ 4≡ 4 y ≡ 2≡ 2≡ 2≡ 2
x1
© 2010 W. W. Norton & Company, Inc. 21
Technologies with Multiple Technologies with Multiple
Inputs
The complete collection of isoquants
The complete collection of isoquants is the isoquant map.
is the isoquant map.
The isoquant map is equivalent to
the production function -- each is the other.
other.
E.g.E.g.
y y ==== ==== f f ( ( x x
11, , x x
22) ) ==== ==== 2 2 x x
111 / 3x x
122 / 3© 2010 W. W. Norton & Company, Inc. 22
Technologies with Multiple Technologies with Multiple
Inputs
x2
y x1
y
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Technologies with Multiple Technologies with Multiple
Inputs
x x2
y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
x2
y y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
x2
y y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
x2
y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
x2 x2
y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
y y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
y y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
y y
x1
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Technologies with Multiple Technologies with Multiple
Inputs
y y
x1
© 2010 W. W. Norton & Company, Inc. 38
Cobb-Douglas Technologies Cobb-Douglas Technologies
A Cobb-Douglas production function is of the form
is of the form
y ==== A x a 1 x a 2 ×××× ××××L x a n .
E.g.
y ==== A x 1a 1 x a2 2 ×××× ××××L x na n .
E.g.
y ==== x
11 / 3x
1 / 32with
y ==== x
1x
2n ==== 2 A ==== 1 a ==== 1 a n d a ==== 1
1 2
, , .
n ==== 2 A ==== 1 a ==== a n d a ====
3 3
1 2
, , .
© 2010 W. W. Norton & Company, Inc. 39
Cobb-Douglas Technologies
x2
All isoquants are hyperbolic,
Cobb-Douglas Technologies
All isoquants are hyperbolic, asymptoting to, but never
asymptoting to, but never touching any axis.
a a
====
y ==== x
1a 1x
a2 2x1
© 2010 W. W. Norton & Company, Inc. 40
Cobb-Douglas Technologies
x2
All isoquants are hyperbolic,
Cobb-Douglas Technologies
All isoquants are hyperbolic, asymptoting to, but never
asymptoting to, but never touching any axis.
a a
====
y ==== x
1a 1x
a2 2x 1a 1 x a2 2 ==== y "
x 1 1 x 2 2 ==== y "
x1
© 2010 W. W. Norton & Company, Inc. 41
Cobb-Douglas Technologies
x2
All isoquants are hyperbolic,
Cobb-Douglas Technologies
All isoquants are hyperbolic, asymptoting to, but never
asymptoting to, but never touching any axis.
a a
====
y ==== x
1a 1x
a2 2x 1a 1 x a2 2 ==== y "
x 1a 1 x a2 2 ==== y ' x 1 1 x 2 2 ==== y "
x1
x 1 x 2 ==== y '
© 2010 W. W. Norton & Company, Inc. 42
Cobb-Douglas Technologies
x2
All isoquants are hyperbolic,
Cobb-Douglas Technologies
All isoquants are hyperbolic, asymptoting to, but never
asymptoting to, but never touching any axis.
a a
y " > y '
y ==== ==== x
1a 1x
a2 2x 1a 1 x a2 2 ==== y "
y " > '
x 1a 1 x a2 2 ==== y ' x 1 1 x 2 2 ==== y "
x1
x 1 x 2 ==== y '
© 2010 W. W. Norton & Company, Inc. 43
Fixed-Proportions Technologies Fixed-Proportions Technologies
A fixed-proportions production function is of the form
function is of the form
y ==== m i n { a x1 1 , a x2 2 , L , a xn n } . E.g.
y ==== m i n { a x1 1 , a x2 2 , L , a xn n } .
E.g.
y ==== m i n { x
1, 2 x
2}
with
y ==== m i n { x
1, 2 x
2}
n ==== 2 , a 1 ==== 1 a n d a 2 ==== 2 . n ==== 2 , a 1 ==== 1 a n d a 2 ==== 2 .
© 2010 W. W. Norton & Company, Inc. 44
Fixed-Proportions Technologies Fixed-Proportions Technologies
x
y ==== m i n { x
1, 2 x
2}
x2
y ==== m i n { x
1, 2 x
2}
x1 = 2x2
min{x1,2x2} = 14 4
7
min{x ,2x } = 8 24 min{x1,2x2} = 8
min{x1,2x2} = 4 x1
4 8 14
min{x1,2x2} = 4
© 2010 W. W. Norton & Company, Inc. 45
Perfect-Substitutes Technologies Perfect-Substitutes Technologies
A perfect-substitutes production function is of the form
function is of the form
y ==== a x1 1 ++++ a x2 2 ++++ L ++++ a n x n .
E.g.
y ==== a x1 1 ++++ a x2 2 ++++ L ++++ a n x n .
E.g.
y ==== x
1++++ 3 x
2with
y ==== x
1++++ 3 x
2n ==== 2 , a 1 ==== 1 a n d a 2 ==== 3 . n ==== 2 , a 1 ==== 1 a n d a 2 ==== 3 .
© 2010 W. W. Norton & Company, Inc. 46
Perfect-Substitution Perfect-Substitution
Technologies
x
y ==== x
1++++ 3 x
2x2
x1 + 3x2 = 18 x1 + 3x2 = 18
x1 + 3x2 = 36
8
x1 + 3x2 = 36
x1 + 3x2 = 48
6
8 x1 + 3x2 = 48
All are linear and parallel
3
6 All are linear and parallel
9 18 24 x1
© 2010 W. W. Norton & Company, Inc. 47
Marginal (Physical) Products Marginal (Physical) Products
y ==== f x (
1, L , x
n)
The marginal product of input i is the
y ==== f x (
1, L , x
n)
The marginal product of input i is the rate-of-change of the output level as rate-of-change of the output level as the level of input i changes, holding all other input levels fixed.
all other input levels fixed.
That is,
y
M P ==== ∂∂∂∂
That is,
i
i
x
M P y
∂∂∂∂
==== ∂∂∂∂
x
i∂∂∂∂
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Marginal (Physical) Products Marginal (Physical) Products
E.g. if E.g. if
y ==== f x( 1 , x 2 ) ==== x 11 / 3 x 22 3/ y ==== f x( 1 , x 2 ) ==== x 1 x 2
then the marginal product of input 1 is
© 2010 W. W. Norton & Company, Inc. 49
Marginal (Physical) Products Marginal (Physical) Products
E.g. if E.g. if
y ==== f x( 1 , x 2 ) ==== x 11 / 3 x 22 3/ y ==== f x( 1 , x 2 ) ==== x 1 x 2
then the marginal product of input 1 is
M P y
x x x
1 1 2 3
22 3
1
====
∂∂∂∂
==== 3 −−−−∂∂∂∂
x / /1
1
1 2
∂∂∂∂
3© 2010 W. W. Norton & Company, Inc. 50
Marginal (Physical) Products Marginal (Physical) Products
E.g. if E.g. if
y ==== f x( 1 , x 2 ) ==== x 11 / 3 x 22 3/ y ==== f x( 1 , x 2 ) ==== x 1 x 2
then the marginal product of input 1 is
M P y
x x x
1 1 2 3
22 3
1
====
∂∂∂∂
==== 3 −−−−∂∂∂∂
x / /1
1
1 2
∂∂∂∂
3and the marginal product of input 2 is and the marginal product of input 2 is
© 2010 W. W. Norton & Company, Inc. 51
Marginal (Physical) Products Marginal (Physical) Products
E.g. if E.g. if
y ==== f x( 1 , x 2 ) ==== x 11 / 3 x 22 3/ y ==== f x( 1 , x 2 ) ==== x 1 x 2
then the marginal product of input 1 is
M P y
x x x
1 1 2 3
22 3
1
====
∂∂∂∂
==== 3 −−−−∂∂∂∂
x / /1
1
1 2
∂∂∂∂
3and the marginal product of input 2 is and the marginal product of input 2 is
M P y
x x x
2 11 / 3
2 1 / 3
2
==== ∂∂∂∂ ==== 3 −−−−
∂∂∂∂ .
M P 2 x x x
2 1 2
==== ==== 3
∂∂∂∂ .
© 2010 W. W. Norton & Company, Inc. 52
Marginal (Physical) Products Marginal (Physical) Products
Typically the marginal product of one Typically the marginal product of one
input depends upon the amount used of input depends upon the amount used of other inputs. E.g. if
M P 1 x 2 3 x 2 3
==== −−−− / /
M P1 1 x 1 2 3 x 22 3
==== 3 −−−− / / then,
M P 1 x 2 3 2 3 4 x 2 3
==== −−−− / / ==== −−−− /
M P1 1 x 1 2 3 2 3 x 1 2 3
3 8 4
==== −−−− / / ==== 3 −−−− /
and if x = 27 then if x2 = 8,
and if x2 = 27 then
M P 1 x 2 3 2 3 x 2 3
2 7 3
==== −−−− / / ==== −−−− / .
M P1 1 x 1 2 3 2 3 x 1 2 3
3 2 7 3
==== −−−− / / ==== −−−− / .
© 2010 W. W. Norton & Company, Inc. 53
Marginal (Physical) Products Marginal (Physical) Products
The marginal product of input i is
diminishing if it becomes smaller as diminishing if it becomes smaller as the level of input i increases. That is, the level of input i increases. That is,
if 2
i y y
M P ∂∂∂∂ ∂∂∂∂ ∂∂∂∂
∂∂∂∂ 0 .
2 2 <<<<
====
====
i i i
i i
x y x
y x
x M P
∂∂∂∂
∂∂∂∂
∂∂∂∂
∂∂∂∂
∂∂∂∂
∂∂∂∂
∂∂∂∂
∂∂∂∂
i i
i
i x x x
x ∂∂∂∂ ∂∂∂∂ ∂∂∂∂
∂∂∂∂
© 2010 W. W. Norton & Company, Inc. 54
Marginal (Physical) Products Marginal (Physical) Products
E.g. if y ==== x 1 / 3 x 2 3/ then M P 1 x 2 3 x 2 3
==== −−−− / / and M P ==== 2 x 1 / 3 x −−−− 1 / 3 E.g. if y ==== x 11 / 3 x 22 3/ then
M P 1 1 x 1 2 3 x 22 3
==== 3 −−−− / / M P 2 2 x 11 / 3 x 2 1 / 3
==== 3 −−−−
and
© 2010 W. W. Norton & Company, Inc. 55
Marginal (Physical) Products Marginal (Physical) Products
E.g. if y ==== x 1 / 3 x 2 3/ then M P 1 x 2 3 x 2 3
==== −−−− / / and M P ==== 2 x 1 / 3 x −−−− 1 / 3 E.g. if y ==== x 11 / 3 x 22 3/ then
M P 1 1 x 1 2 3 x 22 3
==== 3 −−−− / / M P 2 2 x 11 / 3 x 2 1 / 3
==== 3 −−−−
and so ∂∂∂∂ M P 2
so ∂∂∂∂
∂∂∂∂
M P
x 1 x x
1 1 5 3
22 3
2
9 0
==== −−−− −−−− / / <<<<
∂∂∂∂ x 1 9
© 2010 W. W. Norton & Company, Inc. 56
Marginal (Physical) Products Marginal (Physical) Products
E.g. if y ==== x 1 / 3 x 2 3/ then M P 1 x 2 3 x 2 3
==== −−−− / / and M P ==== 2 x 1 / 3 x −−−− 1 / 3 E.g. if y ==== x 11 / 3 x 22 3/ then
M P 1 1 x 1 2 3 x 22 3
==== 3 −−−− / / M P 2 2 x 11 / 3 x 2 1 / 3
==== 3 −−−−
and so ∂∂∂∂ M P 2
so ∂∂∂∂
∂∂∂∂
M P
x 1 x x
1 1 5 3
22 3
2
9 0
==== −−−− −−−− / / <<<<
∂∂∂∂ x 1 9
∂∂∂∂ M P
x x
2 2 1 / 3 4 3
==== −−−− −−−− / <<<< 0 .
and ∂∂∂∂
∂∂∂∂
M P
x 2 x x
2 11 / 3
2 4 3
2
9 0
==== −−−− −−−− / <<<< .
© 2010 W. W. Norton & Company, Inc. 57
Marginal (Physical) Products Marginal (Physical) Products
E.g. if y ==== x 1 / 3 x 2 3/ then M P 1 x 2 3 x 2 3
==== −−−− / / and M P ==== 2 x 1 / 3 x −−−− 1 / 3 E.g. if y ==== x 11 / 3 x 22 3/ then
M P 1 1 x 1 2 3 x 22 3
==== 3 −−−− / / M P 2 2 x 11 / 3 x 2 1 / 3
==== 3 −−−−
and so ∂∂∂∂ M P 2
so ∂∂∂∂
∂∂∂∂
M P
x 1 x x
1 1 5 3
22 3
2
9 0
==== −−−− −−−− / / <<<<
∂∂∂∂ x 1 9
∂∂∂∂ M P
x x
2 2 1 / 3 4 3
==== −−−− −−−− / <<<< 0 .
and ∂∂∂∂
∂∂∂∂
M P
x 2 x x
2 11 / 3
2 4 3
2
9 0
==== −−−− −−−− / <<<< .
Both marginal products are diminishing.
Both marginal products are diminishing.
© 2010 W. W. Norton & Company, Inc. 58
Returns-to-Scale Returns-to-Scale
Marginal products describe the change in output level as a single change in output level as a single input level changes.
input level changes.
Returns-to-scale describes how the output level changes as all input
levels change in direct proportion levels change in direct proportion (e.g. all input levels doubled, or halved).
halved).
© 2010 W. W. Norton & Company, Inc. 59
Returns-to-Scale Returns-to-Scale
If, for any input bundle (x ,…,x ), If, for any input bundle (x1,…,xn),
f k x( 1 , k x 2 , L , k x n ) ==== k f x( 1 , x 2 , L , x n ) f k x( 1 , k x 2 , L , k x n ) ==== k f x( 1 , x 2 , L , x n ) then the technology described by the then the technology described by the production function f exhibits constant returns-to-scale.
returns-to-scale.
E.g. (k = 2) doubling all input levels E.g. (k = 2) doubling all input levels doubles the output level.
© 2010 W. W. Norton & Company, Inc. 60
Returns-to-Scale Returns-to-Scale
One input, one output
Output Level
One input, one output
y = f(x) 2y’
2y’
Constant
y’
Constant
returns-to-scale
x’ x
Input Level 2x’
© 2010 W. W. Norton & Company, Inc. 61
Input Level
Returns-to-Scale Returns-to-Scale
If, for any input bundle (x ,…,x ), If, for any input bundle (x1,…,xn),
f k x( 1 , k x 2 , L , k x n ) <<<< k f x( 1 , x 2 , L , x n ) f k x( 1 , k x 2 , L , k x n ) <<<< k f x( 1 , x 2 , L , x n )
then the technology exhibits diminishing then the technology exhibits diminishing returns-to-scale.
E.g. (k = 2) doubling all input levels less E.g. (k = 2) doubling all input levels less than doubles the output level.
than doubles the output level.
© 2010 W. W. Norton & Company, Inc. 62
Returns-to-Scale Returns-to-Scale
One input, one output
Output Level
One input, one output
y = f(x) 2f(x’)
f(2x’)
Decreasing
f(x’)
Decreasing
returns-to-scale
x’ x
Input Level 2x’
© 2010 W. W. Norton & Company, Inc. 63
Input Level
Returns-to-Scale Returns-to-Scale
If, for any input bundle (x ,…,x ), If, for any input bundle (x1,…,xn),
f k x( 1 , k x 2 , L , k x n ) >>>> k f x( 1 , x 2 , L , x n ) f k x( 1 , k x 2 , L , k x n ) >>>> k f x( 1 , x 2 , L , x n ) then the technology exhibits increasing then the technology exhibits increasing returns-to-scale.
E.g. (k = 2) doubling all input levels E.g. (k = 2) doubling all input levels more than doubles the output level.
more than doubles the output level.
© 2010 W. W. Norton & Company, Inc. 64
Returns-to-Scale Returns-to-Scale
One input, one output
Output Level
One input, one output
y = f(x)
Increasing
returns-to-scale
f(2x’)
returns-to-scale
2f(x’) f(x’) 2f(x’)
x’ x
Input Level
2x’
© 2010 W. W. Norton & Company, Inc. 65
Input Level
Returns-to-Scale Returns-to-Scale
A single technology can ‘locally’
exhibit different returns-to-scale.
exhibit different returns-to-scale.
© 2010 W. W. Norton & Company, Inc. 66
Returns-to-Scale Returns-to-Scale
One input, one output
Output Level
One input, one output
y = f(x)
Increasing y = f(x)
Increasing
returns-to-scale
Decreasing returns-to-scale
Decreasing
returns-to-scale
x Input Level
© 2010 W. W. Norton & Company, Inc. 67
Input Level
Examples of Returns-to-Scale Examples of Returns-to-Scale
The perfect-substitutes production
y ==== a x ++++ a x ++++ ++++ a x .
The perfect-substitutes production function is
y ==== a x1 1 ++++ a x2 2 ++++ L ++++ a n x n .
Expand all input levels proportionately Expand all input levels proportionately by k. The output level becomes
by k. The output level becomes
a 1 ( k x 1 ) ++++ a 2 ( k x 2 ) ++++ L ++++ a n ( k x n )
© 2010 W. W. Norton & Company, Inc. 68
Examples of Returns-to-Scale Examples of Returns-to-Scale
The perfect-substitutes production
y ==== a x ++++ a x ++++ ++++ a x .
The perfect-substitutes production function is
y ==== a x1 1 ++++ a x2 2 ++++ L ++++ a n x n .
Expand all input levels proportionately Expand all input levels proportionately by k. The output level becomes
by k. The output level becomes
a k x a k x a k x
k a x a x a x
n n
n n
1 1 2 2
1 1 2 2
( ) ( ) ( )
( )
++++ ++++ ++++
==== ++++ ++++ ++++
L
k a x( 1 1 a x2 2 L a xn n )
==== ++++ ++++ L ++++
© 2010 W. W. Norton & Company, Inc. 69
Examples of Returns-to-Scale Examples of Returns-to-Scale
The perfect-substitutes production
y ==== a x ++++ a x ++++ ++++ a x .
The perfect-substitutes production function is
y ==== a x1 1 ++++ a x2 2 ++++ L ++++ a n x n .
Expand all input levels proportionately Expand all input levels proportionately by k. The output level becomes
by k. The output level becomes
a k x a k x a k x
k a x a x a x
n n
n n
1 1 2 2
1 1 2 2
( ) ( ) ( )
( )
++++ ++++ ++++
==== ++++ ++++ ++++
L
k a x a x L a x
k y
n n
1 1 2 2
( )
.
==== ++++ ++++ ++++
====
L
The perfect-substitutes production
function exhibits constant returns-to-scale.
© 2010 W. W. Norton & Company, Inc. 70
function exhibits constant returns-to-scale.
Examples of Returns-to-Scale Examples of Returns-to-Scale
The perfect-complements production
y ==== m i n { a x , a x , , a x } .
The perfect-complements production function is
y ==== m i n { a x1 1 , a x2 2 , L , a n x n } .
Expand all input levels proportionately Expand all input levels proportionately by k. The output level becomes
by k. The output level becomes
m i n { a 1 ( k x 1 ) , a 2 ( k x 2 ) , L , a n ( k x n ) }
© 2010 W. W. Norton & Company, Inc. 71
Examples of Returns-to-Scale Examples of Returns-to-Scale
The perfect-complements production
y ==== m i n { a x , a x , , a x } .
The perfect-complements production function is
y ==== m i n { a x1 1 , a x2 2 , L , a n x n } .
Expand all input levels proportionately Expand all input levels proportionately by k. The output level becomes
by k. The output level becomes
m i n { ( ) , ( ) , , ( ) }
( m i n { , , , } )
a k x a k x a k x
k a x a x a x
n n
n n
1 1 2 2
1 1 2 2
L
==== k ( m i n { a x1 1 , a x2 2 , LL , a xn n } )
====
© 2010 W. W. Norton & Company, Inc. 72
Examples of Returns-to-Scale Examples of Returns-to-Scale
The perfect-complements production
y ==== m i n { a x , a x , , a x } .
The perfect-complements production function is
y ==== m i n { a x1 1 , a x2 2 , L , a n x n } .
Expand all input levels proportionately Expand all input levels proportionately by k. The output level becomes
by k. The output level becomes
m i n { ( ) , ( ) , , ( ) }
( m i n { , , , } )
a k x a k x a k x
k a x a x a x
n n
n n
1 1 2 2
1 1 2 2
L
==== ( m i n { , , L , } )
.
k a x a x a x
k y
n n
1 1 2 2 L
====
====
The perfect-complements production
function exhibits constant returns-to-scale.
© 2010 W. W. Norton & Company, Inc. 73
function exhibits constant returns-to-scale.
Examples of Returns-to-Scale Examples of Returns-to-Scale
The Cobb-Douglas production function is
y ==== x 1a 1 x a2 2 L x na n .
The Cobb-Douglas production function is
1 2 n
Expand all input levels proportionately by k. The output level becomes
by k. The output level becomes
( k x 1 ) a 1 ( k x 2 ) a 2 L ( k x n ) a n ( k x 1 ) ( k x 2 ) L ( k x n )
© 2010 W. W. Norton & Company, Inc. 74
Examples of Returns-to-Scale Examples of Returns-to-Scale
The Cobb-Douglas production function is
y ==== x 1a 1 x a2 2 L x na n .
The Cobb-Douglas production function is
1 2 n
Expand all input levels proportionately by k. The output level becomes
by k. The output level becomes
( k x 1 ) a 1 ( k x 2 ) a 2 L ( k x n ) a n ( k x ) ( k x ) ( k x )
k k k x x x
n
a a a n a a a n
1 2
1 2 1 2
L
L L
====
© 2010 W. W. Norton & Company, Inc. 75
Examples of Returns-to-Scale Examples of Returns-to-Scale
The Cobb-Douglas production function is
y ==== x 1a 1 x a2 2 L x na n .
The Cobb-Douglas production function is
1 2 n
Expand all input levels proportionately by k. The output level becomes
by k. The output level becomes
( k x 1 ) a 1 ( k x 2 ) a 2 L ( k x n ) a n ( k x ) ( k x ) ( k x )
k k k x x x
n
a a a n a a a n
1 2
1 2 1 2
L
L L
====
k a 1 a 2 L a n x 1a 1 x a2 2 L x na n
==== ++++ ++++ ++++
© 2010 W. W. Norton & Company, Inc. 76