On Restricted Least Squares: the Cobb-Douglas Production ...

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Developing Country Studies ISSN 2224-607X (Paper) ISSN 2225-0565 (O Vol 2, No.8, 2012 On Restricted Lea Funct ADETUNJI, Ademola 1. adecap 2. Department of Mathematics and Sta Abstract The Cobb-Douglas production func empirical analyses of growth and p economy from 1990 to 2009 and us linear restriction of Cobb-Douglas p Using data on Nigeria’s Gross Dom Nigerian economy is probably char using the restricted regression as Capital/Labour ratio increased by 1 p Keywords: Regression, Restricted 1. Introduction In economic, the Cobb-Douglas fun output and two inputs. It was dev Douglas during 1900 – 1947, (Doug work of (Cobb and Douglas, 1928), researchers like (Brown, 1966); (Sa have been given to Wicksell for its Douglas, 1928) were not the first ec that Wicksell employed the Cobb-D also notes that Pareto used the Cobb parameters of aggregate production f productivity, and labour. Empirical macroeconomics, and important theo for labour, are based on them, (Felip In its most standard form for produ function is: Y = AL β K θ Y = total production (like the monet A = Total factor productivity L = Labour input K = Capital input β and θ = output elasticities of Labo Cobb and Douglas were influenced total output were constant over tim squares regression of their productio In stochastic form, Cobb-Douglas fu Y = output of a production process (l X 1i = input 1 (one of the inputs that c X 2i = input 2 (the second input that c u = stochastic disturbance term e = base of natural logarithm Online) 68 ast Squares: the Cobb-Douglas P tion for the Nigerian Economy a A 1 IBRAHEEM, Ademola G 2 ADEMUYIWA, J [email protected] +2348060754267 (Correspo [email protected] +2348032271 3. [email protected] +234806760482 atistics, The Federal Polytechnic, P.M.B. 5351, Ado-Ek ction (Y = AL β K θ ) is still today the most ubiquitous productivity (Felipe and Adams, 2005). This paper e ses the “F-test” approach of Restricted Least Square ( production function’s parameters (β + θ) = 1 is significa mestic Product (GDP), Capital and total labour force racterized by constant returns to scale over the sampl stipulated by Cobb-Douglas function may not be percent, on average, labour productivity went up by ab d Least Square, Cobb-Douglas, Returns to Scale nctional form of production is widely used to repres veloped and tested against statistical evidence by C glas, 1976). The origin of the Cobb-Douglas form is da who used data for the U.S. manufacturing sector for 1 andelin, 1976); and (Samuelson, 1979) had indicated s discovery since he started working on it in the 19th conomists to use the functional form named after them Douglas functional form in production analysis, twen b-Douglas functional form to represent Utility in 1892 functions is central to many of today’s works on growth estimates of aggregate production functions are essen oretical constructs, such as potential output, technical pe and Adams, 2005). uction of a single good (output) with two factors (inpu tary value of all goods in a year) our and Capital respectively by statistical evidence that applied to show that labou me in developed countries. They explained this by s on function, (Gujarati and Sangeetha, 2007). unction becomes: like GDP of a country) contributes to the output Y e.g. labour) contributes to the output Y e.g. capital) www.iiste.org Production Justus A 3 onding Author) 1093 23 kiti, Ekiti State, Nigeria form in theoretical and examines the Nigerian (RLS) to find out if the ant to Nigeria economy. e, it was found that the le period and therefore, misleading. Hence, if bout 1 percent. sent the relationship of Charles Cobb and Paul ated back to the original 1899 – 1922. Although, d that the credit should h century. (Cobb and m. (Weber, 1998) notes nty years earlier. Weber 2. The estimation of the h, technological change, ntial tools of analysis in l change, or the demand uts), the Cobb-Douglas ur and capital shares of statistically fitting least (i)

Transcript of On Restricted Least Squares: the Cobb-Douglas Production ...

Page 1: On Restricted Least Squares: the Cobb-Douglas Production ...

Developing Country Studies

ISSN 2224-607X (Paper) ISSN 2225-0565 (Online)Vol 2, No.8, 2012

On Restricted Least Squares:

Funct

ADETUNJI, Ademola A

1. [email protected]

2.

Department of Mathematics and Statistics, The Federal Polytechnic, P.M.B. 5351, Ado

Abstract

The Cobb-Douglas production function (

empirical analyses of growth and productivity

economy from 1990 to 2009 and uses the “F

linear restriction of Cobb-Douglas production function’s parameters

Using data on Nigeria’s Gross Domestic Product (GDP), Capital and total labour forc

Nigerian economy is probably characterized by constant returns to scale over the sample period and therefore,

using the restricted regression as stipulated by Cobb

Capital/Labour ratio increased by 1 percent, on average, labour productivity went up by about 1 percent.

Keywords: Regression, Restricted Least Square, Cobb

1. Introduction

In economic, the Cobb-Douglas functional form of production is widely

output and two inputs. It was developed and tested against statistical evidence by Charles Cobb and Paul

Douglas during 1900 – 1947, (Douglas, 1976).

work of (Cobb and Douglas, 1928), who used data for the U.S. manufacturing sector for 1899

researchers like (Brown, 1966); (Sandelin, 1976)

have been given to Wicksell for its disc

Douglas, 1928) were not the first economists to use the functional form named after them.

that Wicksell employed the Cobb-Douglas functional form in production analysi

also notes that Pareto used the Cobb

parameters of aggregate production functions is central to many of today’s works on growth, technological change

productivity, and labour. Empirical estimates of aggregate production functions are essential tools of analysis in

macroeconomics, and important theoretical constructs, such as potential output, technical change, or the demand

for labour, are based on them, (Felipe and Adams, 2005)

In its most standard form for production of a single good (output) with two factors (inputs), the Cobb

function is: Y = ALβK

θ

Y = total production (like the monetary value of all goods in a year)

A = Total factor productivity

L = Labour input

K = Capital input

β and θ = output elasticities of Labour and Capital respectively

Cobb and Douglas were influenced by statistical evidence that applied to show that labour and capital shares of

total output were constant over tim

squares regression of their production function,

In stochastic form, Cobb-Douglas function becomes:

�� � ���������

Y = output of a production process (like GDP of a country)

X1i = input 1 (one of the inputs that contributes to the output Y e.g. labour)

X2i = input 2 (the second input that contributes to the output Y e.g. capital)

u = stochastic disturbance term

e = base of natural logarithm

0565 (Online)

68

On Restricted Least Squares: the Cobb-Douglas Production

Function for the Nigerian Economy

ADETUNJI, Ademola A1

IBRAHEEM, Ademola G2 ADEMUYIWA, Justus A

[email protected] +2348060754267 (Corresponding Author)

[email protected] +2348032271093

3. [email protected] +2348067604823

Department of Mathematics and Statistics, The Federal Polytechnic, P.M.B. 5351, Ado-Ekiti, Ekiti State, Nigeria

Douglas production function (Y = ALβK

θ) is still today the most ubiquitous form in theoretical and

empirical analyses of growth and productivity (Felipe and Adams, 2005). This paper examines the Nigerian

economy from 1990 to 2009 and uses the “F-test” approach of Restricted Least Square (RLS) to find out if the

Douglas production function’s parameters (β + θ) = 1 is significant to Nigeria economy.

Using data on Nigeria’s Gross Domestic Product (GDP), Capital and total labour force, it was found that

Nigerian economy is probably characterized by constant returns to scale over the sample period and therefore,

using the restricted regression as stipulated by Cobb-Douglas function may not be misleading. Hence, if

tio increased by 1 percent, on average, labour productivity went up by about 1 percent.

Regression, Restricted Least Square, Cobb-Douglas, Returns to Scale

Douglas functional form of production is widely used to represent the relationship of

output and two inputs. It was developed and tested against statistical evidence by Charles Cobb and Paul

Douglas, 1976). The origin of the Cobb-Douglas form is dated back to the original

, who used data for the U.S. manufacturing sector for 1899

(Sandelin, 1976); and (Samuelson, 1979) had indicated that the credit should

for its discovery since he started working on it in the 19th century.

were not the first economists to use the functional form named after them.

Douglas functional form in production analysis, twenty years earlier. Weber

also notes that Pareto used the Cobb-Douglas functional form to represent Utility in 1892.

parameters of aggregate production functions is central to many of today’s works on growth, technological change

productivity, and labour. Empirical estimates of aggregate production functions are essential tools of analysis in

macroeconomics, and important theoretical constructs, such as potential output, technical change, or the demand

(Felipe and Adams, 2005).

In its most standard form for production of a single good (output) with two factors (inputs), the Cobb

= total production (like the monetary value of all goods in a year)

= output elasticities of Labour and Capital respectively

Cobb and Douglas were influenced by statistical evidence that applied to show that labour and capital shares of

total output were constant over time in developed countries. They explained this by statistically fitting least

squares regression of their production function, (Gujarati and Sangeetha, 2007).

Douglas function becomes:

= output of a production process (like GDP of a country)

= input 1 (one of the inputs that contributes to the output Y e.g. labour)

= input 2 (the second input that contributes to the output Y e.g. capital)

www.iiste.org

Douglas Production

ADEMUYIWA, Justus A3

+2348060754267 (Corresponding Author)

+2348032271093

+2348067604823

Ekiti, Ekiti State, Nigeria

is still today the most ubiquitous form in theoretical and

This paper examines the Nigerian

roach of Restricted Least Square (RLS) to find out if the

(β + θ) = 1 is significant to Nigeria economy.

e, it was found that the

Nigerian economy is probably characterized by constant returns to scale over the sample period and therefore,

Douglas function may not be misleading. Hence, if

tio increased by 1 percent, on average, labour productivity went up by about 1 percent.

used to represent the relationship of

output and two inputs. It was developed and tested against statistical evidence by Charles Cobb and Paul

Douglas form is dated back to the original

, who used data for the U.S. manufacturing sector for 1899 – 1922. Although,

had indicated that the credit should

overy since he started working on it in the 19th century. (Cobb and

were not the first economists to use the functional form named after them. (Weber, 1998) notes

s, twenty years earlier. Weber

Douglas functional form to represent Utility in 1892. The estimation of the

parameters of aggregate production functions is central to many of today’s works on growth, technological change,

productivity, and labour. Empirical estimates of aggregate production functions are essential tools of analysis in

macroeconomics, and important theoretical constructs, such as potential output, technical change, or the demand

In its most standard form for production of a single good (output) with two factors (inputs), the Cobb-Douglas

Cobb and Douglas were influenced by statistical evidence that applied to show that labour and capital shares of

e in developed countries. They explained this by statistically fitting least

(i)

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Developing Country Studies

ISSN 2224-607X (Paper) ISSN 2225-0565 (Online)Vol 2, No.8, 2012

2. Properties of Cobb-Douglas Production Function

β is the (partial) elasticity of output with respect to the labour input, that is, it measures the percentage change

in output for, say, a 1% change in the labour input, holding the capital input constant.

θ is the (partial) elasticity of output with respe

The sum (β + θ) gives information about the returns to scale, that is, the response of output to a proportionate

change in the inputs.

• If the sum is 1, then, there are constant returns to scale, t

tripling the input will triple the output, and so on.

• If the sum is less than 1, there are decreasing returns to scale

output.

• If the sum is greater than 1, there are increasing returns to scale

the output.

Output elasticity measures the responsiveness of output to a change in levels of either labour or capital

production, ceteris paribus. If (β + θ) = 1, the production function has a constant returns to scale (i.e. the

production output increases by a constant factor). This implies that doubling capital (K) and labour (L) will yield

double output (Y). If (β + θ) < 1, returns to scale are decreasing, and if (β + θ) > 1, returns to scale are

increasing.

3. Literature Review

(Elias, 1992) in (Gujarati and Sangeetha, 2007)

from 1955 – 1974. Using data on the country’s Gross Domestic Product, Employment (labour), and Fixed capital,

they found that Mexican economy was probably characterized by constant returns to scale over the sampled

period and concluded that using Restricted Least Squares obtained for

also observed that increasing capital/employment ratio by 1 percent, on the average will increase the labour

productivity by about 1 percent.

(Effiong and Umoh, 2010) estimated the profit efficiency and the relevant

levels for egg-laying industry in Akwa

stochastic profit frontier. With the aid of a structured questionnaire, they collected primary data from sixty

poultry farms across the six agricultural zones of the state. Empirical results revealed the mean economic

efficiency of 65.00% implying the need for increased resource use efficiency Their results further showed that

variable inputs such as price of feeds, p

that profit decreased with increase in input prices while fixed inputs such as capital inputs and farm size were

statistically significant and had the right sign a

its utilization. Their study suggested that policy that would enhance extension services, encourage membership

in cooperative farming and enhanced good and adequate utilization of improved livestock inp

place.

(Abidemi, 2010) examines productivity in the banking sector by way of estimating two major production

functions known in the economic literature. The result obtained from the Ordinary Least Square (OLS) estimates

shows that substitution parameters α and β (substitution parameters for capital and labour, respectively) confirms

the a priori expectation that the duo of α and β are positive values of less than one. He found that the addition of

the values of α and β is greater than o

capital and labour, the output in terms of deposit will be more than doubled. He also observes that the

substitution parameters in the Constant Elasticity of Substitution Product

which supports the theory. In his final analysis, his study supports economic theory on the specification of both

Cobb-Douglas and Constant Elasticity of Substitution production functions.

In (Abiola, 2010), (Douglas, 19

concluded that labour is the single most important factor of production in a certain subtle sense. Both labour and

capital are needed in production: they opined that when capital is taken

negligible total products will be left with. But they found that a one percent increase in labour seems to increase

output about three times as much as would a one percent increase in capital. This largely corresponds

widely known fact that wages are about three

(Liedholm, 1964) was perhaps the first work to be done on productivity in Nigeria. An attempt was made at

finding out between labour and capital, which input con

Nigeria and it was found that labours’ contribution to the output of the selected manufacturing industries was

larger than that of capital. This position was confirmed by

(Ekanem, 2003) provides estimates of Total Factor Productivity for the banking industry in Nigeria for the

period 1986 – 2000. The methodology in the work involved the use of the Growth Accounting Model based on

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69

Douglas Production Function

is the (partial) elasticity of output with respect to the labour input, that is, it measures the percentage change

in output for, say, a 1% change in the labour input, holding the capital input constant.

is the (partial) elasticity of output with respect to the capital input, holding the labour input constant.

) gives information about the returns to scale, that is, the response of output to a proportionate

If the sum is 1, then, there are constant returns to scale, that is, doubling the inputs will double the output,

tripling the input will triple the output, and so on.

If the sum is less than 1, there are decreasing returns to scale – doubling the inputs will give less double the

there are increasing returns to scale – doubling the inputs will give more double of

Output elasticity measures the responsiveness of output to a change in levels of either labour or capital

production, ceteris paribus. If (β + θ) = 1, the production function has a constant returns to scale (i.e. the

production output increases by a constant factor). This implies that doubling capital (K) and labour (L) will yield

(β + θ) < 1, returns to scale are decreasing, and if (β + θ) > 1, returns to scale are

Gujarati and Sangeetha, 2007) used Restricted Least Squares to observe Mexican Economy

on the country’s Gross Domestic Product, Employment (labour), and Fixed capital,

they found that Mexican economy was probably characterized by constant returns to scale over the sampled

period and concluded that using Restricted Least Squares obtained for the data set could not be harmful. They

also observed that increasing capital/employment ratio by 1 percent, on the average will increase the labour

estimated the profit efficiency and the relevant indices determining efficiency

laying industry in Akwa-Ibom State, Nigeria utilizing Cobb-Douglas production function based on

stochastic profit frontier. With the aid of a structured questionnaire, they collected primary data from sixty

ltry farms across the six agricultural zones of the state. Empirical results revealed the mean economic

efficiency of 65.00% implying the need for increased resource use efficiency Their results further showed that

variable inputs such as price of feeds, price of drugs and medication were statistically significant thus indicating

that profit decreased with increase in input prices while fixed inputs such as capital inputs and farm size were

statistically significant and had the right sign a-priori indicating that profit increased with increase in the level of

its utilization. Their study suggested that policy that would enhance extension services, encourage membership

in cooperative farming and enhanced good and adequate utilization of improved livestock inp

examines productivity in the banking sector by way of estimating two major production

functions known in the economic literature. The result obtained from the Ordinary Least Square (OLS) estimates

titution parameters α and β (substitution parameters for capital and labour, respectively) confirms

the a priori expectation that the duo of α and β are positive values of less than one. He found that the addition of

the values of α and β is greater than one, which indicates that as the banking sector doubles its inputs in terms of

capital and labour, the output in terms of deposit will be more than doubled. He also observes that the

substitution parameters in the Constant Elasticity of Substitution Production Function were equally positive,

which supports the theory. In his final analysis, his study supports economic theory on the specification of both

Douglas and Constant Elasticity of Substitution production functions.

(Abiola, 2010), (Douglas, 1934) and (Solow, 1957) in their study on capital

concluded that labour is the single most important factor of production in a certain subtle sense. Both labour and

capital are needed in production: they opined that when capital is taken away, or alternatively all labour and

negligible total products will be left with. But they found that a one percent increase in labour seems to increase

output about three times as much as would a one percent increase in capital. This largely corresponds

widely known fact that wages are about three-fourth of the share of property incomes.

was perhaps the first work to be done on productivity in Nigeria. An attempt was made at

finding out between labour and capital, which input contributed more to the output of major industries in Eastern

Nigeria and it was found that labours’ contribution to the output of the selected manufacturing industries was

larger than that of capital. This position was confirmed by (Osagie and Odaro, 1975).

provides estimates of Total Factor Productivity for the banking industry in Nigeria for the

2000. The methodology in the work involved the use of the Growth Accounting Model based on

www.iiste.org

is the (partial) elasticity of output with respect to the labour input, that is, it measures the percentage change

ct to the capital input, holding the labour input constant.

) gives information about the returns to scale, that is, the response of output to a proportionate

hat is, doubling the inputs will double the output,

doubling the inputs will give less double the

doubling the inputs will give more double of

Output elasticity measures the responsiveness of output to a change in levels of either labour or capital used in

production, ceteris paribus. If (β + θ) = 1, the production function has a constant returns to scale (i.e. the

production output increases by a constant factor). This implies that doubling capital (K) and labour (L) will yield

(β + θ) < 1, returns to scale are decreasing, and if (β + θ) > 1, returns to scale are

used Restricted Least Squares to observe Mexican Economy

on the country’s Gross Domestic Product, Employment (labour), and Fixed capital,

they found that Mexican economy was probably characterized by constant returns to scale over the sampled

the data set could not be harmful. They

also observed that increasing capital/employment ratio by 1 percent, on the average will increase the labour

indices determining efficiency

Douglas production function based on

stochastic profit frontier. With the aid of a structured questionnaire, they collected primary data from sixty

ltry farms across the six agricultural zones of the state. Empirical results revealed the mean economic

efficiency of 65.00% implying the need for increased resource use efficiency Their results further showed that

rice of drugs and medication were statistically significant thus indicating

that profit decreased with increase in input prices while fixed inputs such as capital inputs and farm size were

g that profit increased with increase in the level of

its utilization. Their study suggested that policy that would enhance extension services, encourage membership

in cooperative farming and enhanced good and adequate utilization of improved livestock inputs should be put in

examines productivity in the banking sector by way of estimating two major production

functions known in the economic literature. The result obtained from the Ordinary Least Square (OLS) estimates

titution parameters α and β (substitution parameters for capital and labour, respectively) confirms

the a priori expectation that the duo of α and β are positive values of less than one. He found that the addition of

ne, which indicates that as the banking sector doubles its inputs in terms of

capital and labour, the output in terms of deposit will be more than doubled. He also observes that the

ion Function were equally positive,

which supports the theory. In his final analysis, his study supports economic theory on the specification of both

in their study on capital-labour substitution

concluded that labour is the single most important factor of production in a certain subtle sense. Both labour and

away, or alternatively all labour and

negligible total products will be left with. But they found that a one percent increase in labour seems to increase

output about three times as much as would a one percent increase in capital. This largely corresponds with the

was perhaps the first work to be done on productivity in Nigeria. An attempt was made at

tributed more to the output of major industries in Eastern

Nigeria and it was found that labours’ contribution to the output of the selected manufacturing industries was

provides estimates of Total Factor Productivity for the banking industry in Nigeria for the

2000. The methodology in the work involved the use of the Growth Accounting Model based on

Page 3: On Restricted Least Squares: the Cobb-Douglas Production ...

Developing Country Studies

ISSN 2224-607X (Paper) ISSN 2225-0565 (Online)Vol 2, No.8, 2012

aggregate production functions. In the study

production process of the industry in Nigeria was found to be the Cobb

estimated Cobb-Douglas function were used to calibrate the Growth Accounting Model. The res

measured aggregate output grew at an average annual rate of 4.29%, while Total Factor Productivity grew at an

average annual rate of 3.33%. The study analyzed that TFP provided 78% of the recorded growth in the industry

during this period.

(Ekanem and Oyefusi, 2000) estimated the Cobb

production functions for the manufacturing industry in Nigeria for the period 1980

consideration the phenomenon of idle capacity th

models when compared with the work of

results in terms of goodness of fit. Of the two production functions estimated, the Cobb

Function performs better considering all the relevant econometric test criteria. This then showed that the

Cobb-Douglas Production Function gives a better explanation of the aggregate production process in the

manufacturing industry in Nigeria for the period studied.

4. Materials and Method

The dataset used for this research work are Real Gross Domestic Product and Capital expenditure has obtained

from Central Bank of Nigeria’s Statistical Bulletin, 2011 and the total labour force of Ni

obtained from World Bank national accounts data, and OECD National Accounts data files.

Written (i) in log form, the equation becomes:

ln �� � ln � � � ln ��� � � ln �� � �ln �� � � � � ln ��� � � ln �� � �� If there are constant returns to scale (equiproportional change in output for an equiproportional change in the

input), economic theory suggests that β + θ = 1. This is a form of linear equality

the validity of (ii), there are two possible approaches.

The t-Test Approach (The unrestricted/unconstrained Regression)

This procedure involves estimating parameters of (iii) without considering the linear equality restric

1) explicitly by using Ordinary Least Squares (OLS) method. Having estimated β and θ, a test of

hypothesis/restriction is conducted using t

�� � ���� ������������� ������� !"#���$

The test statistic is compared with

observation and k is the number of estimated parameters in (iii) and appropriate decision is taken on the set

hypothesis {H0: (β+θ) = 1}

The F-Test Approach (Restricted Least Square, RLS)

The t-test approach is post-mortem in that it only finds out whether the linear restriction is satisfied after

estimating the unrestricted regression. However, the F

into the estimating procedure at the outset.

Since β + θ = 1, hence β = 1 – θ. Substituting (1

ln �� � � � #1 & �$ ln ��� � � ln �ln �� � � � ln ��� & � ln ��� � � ln �#ln �� & ln ���$ � � � � #ln �� & lnln#��/���$ � � � � ln#��/���$ �Variables #��/���$ and #��/���$

output with one of the inputs and #estimated from (v), β can be estimated using β = 1

The overall implication of this is that the procedure ensures that sum of the estimated coefficients of the two

inputs equal 1 and hence, the name “Restricted Least Squares, RLS”. The generalization of this procedure into

more than one linear equality restriction is explained by

Examining the validity of RLS

The validity of the Restricted Least Squares can be examined by applying F

0565 (Online)

70

aggregate production functions. In the study, the most appropriate production function that describes the

production process of the industry in Nigeria was found to be the Cobb- Douglas. The parameters of the

Douglas function were used to calibrate the Growth Accounting Model. The res

measured aggregate output grew at an average annual rate of 4.29%, while Total Factor Productivity grew at an

average annual rate of 3.33%. The study analyzed that TFP provided 78% of the recorded growth in the industry

estimated the Cobb-Douglas and the Constant Elasticity of Substitution (CES)

production functions for the manufacturing industry in Nigeria for the period 1980

consideration the phenomenon of idle capacity that has characterized the industry at the time. The results of the

models when compared with the work of (Liedholm, 1964) and (Osagie and Odaro, 1975)

results in terms of goodness of fit. Of the two production functions estimated, the Cobb

Function performs better considering all the relevant econometric test criteria. This then showed that the

Douglas Production Function gives a better explanation of the aggregate production process in the

Nigeria for the period studied.

The dataset used for this research work are Real Gross Domestic Product and Capital expenditure has obtained

from Central Bank of Nigeria’s Statistical Bulletin, 2011 and the total labour force of Ni

World Bank national accounts data, and OECD National Accounts data files.

Written (i) in log form, the equation becomes:

��

#ln � � �$

If there are constant returns to scale (equiproportional change in output for an equiproportional change in the

input), economic theory suggests that β + θ = 1. This is a form of linear equality restriction. In order to examine

the validity of (ii), there are two possible approaches.

Test Approach (The unrestricted/unconstrained Regression)

This procedure involves estimating parameters of (iii) without considering the linear equality restric

1) explicitly by using Ordinary Least Squares (OLS) method. Having estimated β and θ, a test of

hypothesis/restriction is conducted using t-test where the test statistic is given by:

The test statistic is compared with �() #* & +$ where α is the level of significance, n is the number of

observation and k is the number of estimated parameters in (iii) and appropriate decision is taken on the set

Test Approach (Restricted Least Square, RLS)

mortem in that it only finds out whether the linear restriction is satisfied after

estimating the unrestricted regression. However, the F-test approach incorporates the linear equality restriction

into the estimating procedure at the outset.

θ. Substituting (1 – θ) for β in (iii) gives:

� � ��

�� � ��

ln ���$ � ��

��

are of great economic importance since #��/���$ measures the ratio of the

#��/���$ compares one of the input variables with the other. Once θ can be

estimated from (v), β can be estimated using β = 1 – θ.

The overall implication of this is that the procedure ensures that sum of the estimated coefficients of the two

inputs equal 1 and hence, the name “Restricted Least Squares, RLS”. The generalization of this procedure into

restriction is explained by (Theil, 1971).

The validity of the Restricted Least Squares can be examined by applying F-test where

www.iiste.org

, the most appropriate production function that describes the

Douglas. The parameters of the

Douglas function were used to calibrate the Growth Accounting Model. The results showed that

measured aggregate output grew at an average annual rate of 4.29%, while Total Factor Productivity grew at an

average annual rate of 3.33%. The study analyzed that TFP provided 78% of the recorded growth in the industry

Douglas and the Constant Elasticity of Substitution (CES)

production functions for the manufacturing industry in Nigeria for the period 1980 – 1997, taking into

at has characterized the industry at the time. The results of the

(Osagie and Odaro, 1975) gave satisfactory

results in terms of goodness of fit. Of the two production functions estimated, the Cobb-Douglas Production

Function performs better considering all the relevant econometric test criteria. This then showed that the

Douglas Production Function gives a better explanation of the aggregate production process in the

The dataset used for this research work are Real Gross Domestic Product and Capital expenditure has obtained

from Central Bank of Nigeria’s Statistical Bulletin, 2011 and the total labour force of Nigeria 1990 – 2009

World Bank national accounts data, and OECD National Accounts data files.

(ii)

(iii)

If there are constant returns to scale (equiproportional change in output for an equiproportional change in the

restriction. In order to examine

This procedure involves estimating parameters of (iii) without considering the linear equality restriction (β + θ =

1) explicitly by using Ordinary Least Squares (OLS) method. Having estimated β and θ, a test of

(iv)

where α is the level of significance, n is the number of

observation and k is the number of estimated parameters in (iii) and appropriate decision is taken on the set

mortem in that it only finds out whether the linear restriction is satisfied after

ach incorporates the linear equality restriction

(v)

measures the ratio of the

compares one of the input variables with the other. Once θ can be

The overall implication of this is that the procedure ensures that sum of the estimated coefficients of the two

inputs equal 1 and hence, the name “Restricted Least Squares, RLS”. The generalization of this procedure into

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Developing Country Studies

ISSN 2224-607X (Paper) ISSN 2225-0565 (Online)Vol 2, No.8, 2012

,-�. � #//01� //0231$/�//031/#4�5$

6678 is the sum of squares of error for restricted regression in (v)

66798 is the sum of squares of error for unrestricted regression in (iii)

a is number of linear restriction ( a = 1 in Cobb

k is the number of estimated parameters in (iii)

n is the number of observations

The Fcal is compared with Ftable with [

hypothesis, H0: The Restricted Least Squares (RLS) is not significant. If the RLS is not si

is probably characterized by constant returns to scale over the sampled period and hence, there may be no harm

in using the restricted regression in (v).

5. Results and Discussion

Fitting the Cobb-Douglas production function to the

and total labour force from 1990 to 2009 gives:

ln :;<=> � &129.439208 � 8.095468 t = (-7.609275) (7.644071)

P-value = (0.000001) (0.000001)

Std Err. = (17.010715) (1.059052)

R2 = 0.978207

The equation above (vii) shows that the output/labour elasticity is about 8.

about 0.25. if we add these coefficients, we obtain 8.36, indicating that the Nigeria economy has a very high

increasing returns to scale. As high as this value, it is very essential to subject this finding to statis

hypothesis. Imposing the restriction of constant returns to scale gives the following result:

ln#:;</HIJK�L$=> � 3.785507 t = (6.845303)

P-value =

Std Err. = (0.553008)

R2 = 0.876866

* UR � Unrestricted Regression

Since the independent variables in (vii) and (viii) differ,

,-�. � #6678 & 66798$/I66798/#* & +$ � #3.955770

The Fcal follows the F-distribution

and 5% (4.45) level.

6. Conclusion

The conclusion then is that the Nigerian economy is probably characterized by constant returns to scale over the

sample period and therefore, using the restricted regression as stipulated by Cobb

harmful. Hence, if Capital/Labour ratio increased by 1 percent, on average, labour productivity went up by about

1 percent over the sampled period.

7. Policy Implications

This study examined Cobb-Douglas coefficient’s restriction on Nigeria economy from 1990 to 2009 by way of

estimating the mostly utilized production functions in the economics literature. The result obtained from the OLS

estimates shows that substitution parameters, β and θ do not support economic theory of the duo being positive

values of less than one. The addition of the values of β and θ is greater than one which suggests that as the

Nigeria economy doubles its inputs in terms of labour and capital, the output in terms of GDP will be more than

doubled but a test of significance revealed otherwise. The study su

the Cobb-Douglas and production functions in researching into inputs/output relationship. The study, therefore,

recommends for Nigerian government and those involve in decision making that for desired increase

productivity in terms of output like the GDP, more units of both labour and capital should be employed.

0565 (Online)

71

is the sum of squares of error for restricted regression in (v)

is the sum of squares of error for unrestricted regression in (iii)

a is number of linear restriction ( a = 1 in Cobb-Douglas function)

eters in (iii)

with [a, (n – k)] degree of freedom at specified level of significance with the null

: The Restricted Least Squares (RLS) is not significant. If the RLS is not si

is probably characterized by constant returns to scale over the sampled period and hence, there may be no harm

in using the restricted regression in (v).

Douglas production function to the data on Nigeria’s Gross Domestic Product (GDP), Capital

and total labour force from 1990 to 2009 gives:

095468 ln HIJK�L= � 0.253359 ln NIOP�IQ=

(7.644071) (1.951656)

(0.000001) (0.067654)

(1.059052) (0.129817)

*RSSUR = 38.525827

*SSEUR = 0.858280

The equation above (vii) shows that the output/labour elasticity is about 8.10 and the output/capital elasticity is

about 0.25. if we add these coefficients, we obtain 8.36, indicating that the Nigeria economy has a very high

increasing returns to scale. As high as this value, it is very essential to subject this finding to statis

hypothesis. Imposing the restriction of constant returns to scale gives the following result:

� 1.190436 ln#NIOP�IQ/HIJK�L$= (viii)

(6.845303) (11.321751)

(0.000002) (0.000000)

(0.553008) (0.105146)

^RSSR = 28.169922

^SSER = 3.955770

^ � Restricted Regression

Since the independent variables in (vii) and (viii) differ, Fcal in (vi) is used to obtain F-value

# 955770 & 0.858280$/10.858280/17 � 3.60895

with (1, 17) degree of freedom. Hence, Fcal is significant at both 1% (8.40)

The conclusion then is that the Nigerian economy is probably characterized by constant returns to scale over the

sample period and therefore, using the restricted regression as stipulated by Cobb-Douglas function may not be

l/Labour ratio increased by 1 percent, on average, labour productivity went up by about

Douglas coefficient’s restriction on Nigeria economy from 1990 to 2009 by way of

timating the mostly utilized production functions in the economics literature. The result obtained from the OLS

estimates shows that substitution parameters, β and θ do not support economic theory of the duo being positive

tion of the values of β and θ is greater than one which suggests that as the

Nigeria economy doubles its inputs in terms of labour and capital, the output in terms of GDP will be more than

doubled but a test of significance revealed otherwise. The study supports economic theory in the specification of

Douglas and production functions in researching into inputs/output relationship. The study, therefore,

recommends for Nigerian government and those involve in decision making that for desired increase

productivity in terms of output like the GDP, more units of both labour and capital should be employed.

www.iiste.org

(vi)

degree of freedom at specified level of significance with the null

: The Restricted Least Squares (RLS) is not significant. If the RLS is not significant, the economy

is probably characterized by constant returns to scale over the sampled period and hence, there may be no harm

Nigeria’s Gross Domestic Product (GDP), Capital

(vii)

= 0.858280

10 and the output/capital elasticity is

about 0.25. if we add these coefficients, we obtain 8.36, indicating that the Nigeria economy has a very high

increasing returns to scale. As high as this value, it is very essential to subject this finding to statistical

hypothesis. Imposing the restriction of constant returns to scale gives the following result:

(viii)

value

is significant at both 1% (8.40)

The conclusion then is that the Nigerian economy is probably characterized by constant returns to scale over the

Douglas function may not be

l/Labour ratio increased by 1 percent, on average, labour productivity went up by about

Douglas coefficient’s restriction on Nigeria economy from 1990 to 2009 by way of

timating the mostly utilized production functions in the economics literature. The result obtained from the OLS

estimates shows that substitution parameters, β and θ do not support economic theory of the duo being positive

tion of the values of β and θ is greater than one which suggests that as the

Nigeria economy doubles its inputs in terms of labour and capital, the output in terms of GDP will be more than

pports economic theory in the specification of

Douglas and production functions in researching into inputs/output relationship. The study, therefore,

recommends for Nigerian government and those involve in decision making that for desired increase

productivity in terms of output like the GDP, more units of both labour and capital should be employed.

Page 5: On Restricted Least Squares: the Cobb-Douglas Production ...

Developing Country Studies

ISSN 2224-607X (Paper) ISSN 2225-0565 (Online)Vol 2, No.8, 2012

References

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Douglas, Paul H. (1976): “The Cobb

New Empirical Values". University of Chicago Press,

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laying enterprise in Akwa Ibom State, Nigeria,

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Industry in Nigeria 1980-1997”

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Liedholm, C. E. (1964): Production for Eastern Nigerian I

Social Studies Vol. 24 (1), Pp. 37

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Journal of Political Economy, pp. 923

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pp. 117 – 125

Solow, R.M. (1957): “Technical Change and the Aggregate Production Function”,

Statistics. Vol. 39, pp. 312-320.

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Economic Thought, 20 (2), 203

World Bank national accounts data, and OECD National Accounts data files (2012)

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Labour Substitution and Banking Sector Performance in Nigeria (1960

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New Empirical Values". University of Chicago Press, Journal of Political Economy 84 (5): pp. 903

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(2010): Cobb Douglas Production Function with composite error term in egg

laying enterprise in Akwa Ibom State, Nigeria, Agro-Science Journal of Tropical Agriculture, Food,

olume 9 Number 1, pp. 1-7

Ekanem O.T. (2003), “Productivity in the Banking Industry in Nigerian” Journal of Economics and Social

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1997” Unpublished Work

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Nigerian Manufacturing Industry 1960-1975”. The Nigerian Journal of Economic and Social Studies

Samuelson, P. (1979): Paul Douglas’s Measurement of Production Functions and Marginal Productivities,

pp. 923 – 939

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American Economic Review, pp. 139 – 165

Douglas Production Function Once Again: Its History, Its Testing, and Some

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Journal of the History of

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Developing Country Studies

ISSN 2224-607X (Paper) ISSN 2225-0565 (Online)Vol 2, No.8, 2012

Figure 1

Figure 2

Figures 1 and 2 above show upward movements for the log transformation of all the variables under

consideration.

16

18

20

22

24

26

28

30

32

34

Cobb-Douglas Logarithmic

ln GDP_Current Basic Prices

6

7

8

9

10

11

12

13

14

Cobb-Douglas Logarithmic

ln (GDP/LABOUR)

0565 (Online)

73

Figures 1 and 2 above show upward movements for the log transformation of all the variables under

Year

Douglas Logarithmic-Scale for Nigeria GDP, Capital

and Labour

ln GDP_Current Basic Prices ln Labour ln Capital_Expenditure

Year

Douglas Logarithmic-Scale for (GDP/Capital ) and

(Labour/Capital)

ln (GDP/LABOUR) ln (CAPITAL/LABOUR)

www.iiste.org

Figures 1 and 2 above show upward movements for the log transformation of all the variables under

Scale for Nigeria GDP, Capital

ln Capital_Expenditure

Scale for (GDP/Capital ) and

Page 7: On Restricted Least Squares: the Cobb-Douglas Production ...

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