
© 19992003
Douglas A. Ruby
Revised: 01/18/2003
A Producer Optimum
Production and Production Possibilities
Microeconomic Theory

Production in the Long Run
Production in the long run is distinguished from short run production in that
all factor inputs may be used in varying amounts. Given the production function:
X = f(L, K, M, R),
we find that one factor may be substituted, to some degree, for another
factor of production. Increasing the amount of capital or
machinery 'K' can replace some labor 'L' but not all of the labor
in a production process. Increasing amounts of labor
(greater care being taken in production to avoid waste)
can reduce the need for some material inputs 'M'. In addition,
where all factors of production are allowed to
vary in quantity, proportional increases
in all factors of production may lead to unbounded increases in output.
As we begin to model production in the long run, we will simplify the production
function somewhat as:
X = f(L, K),
where we assume that the extraction of raw materials or the development of land is accomplished
with combinations of labor and capital input. Entrepreneurship is embedded in the production
technology used [f(.)]. This allows for a twodimensional representation of combinations of factor
inputs required to produce chosen levels of output.
Figure 1, Factor Input Combinations
Suppose, for example, it is possible to produce 100 units of output (X = 100) with the following combinations
of labor and capital (press 'X=100' on the diagram):
L 
K 

50 
200 
 Capital Intensive Production 
100 
100 
 Equal Amounts 
200 
50 
 Labor Intensive Production 
Each point represents these input combinations. The lines connecting
each point denote the possibility that an arithmetic average of any of these combinations may also
allow for the production of 100 units of output.
If the production technology allows, we could double the quantity of each input and perhaps
double the amount of output (press 'X = 200'). These points
represent capital and labor combinations that allow for this greater level of output. By tripling
the original quantity of intputs might allow for a tripling of output (press 'X = 300').
The 'kinked' lines in the above diagram are known as Production Isoquants
or "lines of equal output". Each point on a given colored line represents combinations of the two
inputs that allow for a given level of output: X = 100,
X = 200, or X = 300.
Points A,
A', or A'' represent combinations of capital and labor used in a 4:1 ratio in order to produce the three levels of output. In relative terms, this is known as Capital Intensive Production (press the
'K/L Ratio' button in the diagram above).
Figure 2, Production Isoquants
The points C,
C', or C'' represent combinations of capital and labor used in a 1:4 ratio or Labor Intensive Production. For a given production technology it is not possible to say that using one factor more intensively than the other is better or more efficient. In economies where capital is relatively scarce and therefore relative more expensive in use as compared to labor, a labor intensive production process may be more efficient. If the opposite is true (labor being relatively scarce), then capital intensive production may be observed. The actual combination of factor inputs will depend on their relative prodcutivities and existing factor prices.
The three rays representing different production processes (capital intensive, labor intensive, or inbetween), may not be the only options available. Allowing for a continuim of processes results in the 'kinked' production isoquants becomming smoother (press the "IQ's" button). These smooth isoquants represent an infinite number of production processes available.
Returns to Scale
Through an examination of proportional increases in the inputs,
we can define different production technologies with the concept of returns to scale.
This concept refers of the ability to more than double,
exactly double, or less than double the level of
output when the quantity of all the available
inputs are exactly doubled.
For example, in some cases, a production process may be
replicated. Thus
if a certain quantiy of grain is being produced on one
acre of land with 5 units of labor input and 3 pieces of
capital, then by replicating this production process the
quantity of grain produced may be doubled. In this case, the
technology represented is known as
constant returns to scale.
Figure 3, Constant Returns to Scale
Technologies where a doubling of inputs leads to a more than
doubling of outputs is known as increasing
returns to scale. Finally production techologies that
lead to a less than doubling of output when all inputs are doubled
is known as decreasing
returns to scale.
Figure 4, Increasing Returns to Scale

Figure 5, Decreasing Returns to Scale

The CobbDouglas Production Function
One mathematical production relationship that posesses the three
properties listed above (diminishing marginal productivity, essential
inputs, and possibilities for substitution) is the CobbDouglas
production function. This particular
representation is one of several possibilities and may be
written as follows:
X = A_{t}L^{a}K^{b}
where L and K represent the factor inputs listed above,
A represents a measure of technology at time period 't',
and the exponents represent production parameters
(actually output elasticities). The fact that it is
multiplicative in the inputs reflects the notion that one
factor may be substituted for another. Diminishing
marginal productivity requires that the exponents a, b, and
g each take on values less
than one.Each input being essential and making a positive
contribution to output implies that these exponents be
strictly greater than zero.
The different production technologies are defined by the
sum of the production exponents. Constant returns to
scale implies that a, b, and g sum
to one:
X = A_{t}
L^{a}
K^{b}
and
A_{t}(2L)^{a}
(2K)^{b}
=
(2)^{a+b}
A_{t}
L^{a}
K^{b}
=
(2)^{1}
A_{t}
L^{a}
K^{b}
= 2X
With increasing returns to scale these exponents will sum
to a value greater than one and with decreasing returns to scale,
these exponents sum to a value less than one.
Returns to scale represent one dimension of production technology in the
long run. This concept governs how costs change as production levels are altered.
Under constant returns to scale, a doubling of output results in an exact doubling of production costs. In the case of increasing returns, costs increase at a rate less than than change in output such that average (perunit) costs decrease with increasing levels of output. On the other hand, under decreasing returns to scale, costs increase at a rate greater than production. In this case, increasing production levels are matched by increasing perunit costs.
Substitution among factor inputs
A second dimension to production technology is the ease by which one factor may be substituted for another. This may be necessary as relative factor prices change (i.e., wages increase such that labor becomes more expensive relative to capital) and the firm attempts to substitute away from the more expensive factor.
The CobbDouglas production function is just one particular mathematical form consistent with imperfect substitution among factors.
Two extreme cases are a Linear Technology where the production function may be written as:
X = αL + βK
In this case, the factors are perfect substitutes for one another and the profit maximizing firm will use only the relatively cheaper factor of production.
At the other extreme is a Leontief Technology where factors must be used in fixed proportion to oneanother (i.e., in providing passenger services, one bus is matched with one driver):
X = min[αL, βK]
In this case, substitution is not possible and the firm must absorb factor price increases in the form of higher costs.
Figure 4, Elasticity of Substitution
These different expressions may be summarized in a single mathematical form known as the Constant Elasticity of Substitution (CES) production function:
X = A[αL^{ρ} + βK^{ρ}]^{(1/ρ)}
The new paramter introduced 'ρ' is a measure of the ease by which labor may be substituted for capital or viceversa. If the following values of ρ are observed:
ρ = 0  then we have a CobbDouglas technology,
ρ = 1  then we have a Linear technology,
as ρ approaches negative infinity  then then a Leontief technology exists.
Concepts for Review:
 Capital Intensive Production
 CobbDouglas Production Technology
 Constant Elastiticy of Substitution (CES)
 Constant Returns to Scale
 Decreasing Returns to Scale
 Elasticity of Substitution
 Factor Substitution
 Increasing Returns to Scale
 Labor Intensive Production
 Leontief Production Technology
 Linear Production Technology
 [the] Long Run
 Production Isoquant
 Returns to Scale
