energy growth long term relationship under structural breaks evidence from canada 17 latin american economies and the usa abstract we study the relationship and the causal link between electric power consumption epc and gross domestic product gdp both per capita for 17 countries in latin america canada and the usa considering that many of these economies underwent important economic crises in the last three decades we therefore model the epc gdp relationship through a vec specification that allows for structural breaks along with a robust testing methodology of causal links based on the concepts of weak and super exogeneity rather than granger causality evidence favorable to the growth hypothesis epc gdp is found for eight countries while data of three countries support the conservation hypothesis gdp epc for three countries evidence is favorable to the neutrality hypothesis but should be considered with caution as for the remaining five countries the evidence is not conclusive

energy consumption and economic growth revisited does the size of unrecorded economy matter abstract we analyze the long run relationship between energy consumption and real gross domestic product gdp in turkey taking into account the size of unrecorded economy since in developing countries mainly due to the unrecorded economic activities the official gdp is not measured correctly the investigation of the linkage between energy consumption and official gdp may not give reliable results in this study empirical results for the case of turkey over the period 1970 2005 suggest that there is a long run equilibrium relationship between the officially calculated gdp and energy consumption besides using the error correction modeling technique we find out that unidirectional causality runs from official gdp to energy in both short and long runs however when we take into account unrecorded economy we detect neither cointegration nor causality between energy consumption and true gdp these empirical findings imply that first energy conservation policies can be implemented in order to reduce greenhouse gas emissions without any adverse effect on the recorded economic activities second the production function in the unrecorded economy is not stable furthermore economic policies to combat unrecorded economy may not serve as a complement to energy conservation policies

energy consumption and gdp in developing countries a cointegrated panel analysis in this paper we re investigate the co movement and the causality relationship between energy consumption and gdp in 18 developing countries using data for the period 1975 to 2001 recently developed tests for the panel unit root heterogeneous panel cointegration and panel based error correction models are employed the empirical results provide clear support of a long run cointegration relationship after allowing for the heterogeneous country effect the long run relationship is estimated using a full modified ols the evidence shows that long run and short run causalities run from energy consumption to gdp but not vice versa this result indicates that energy conservation may harm economic growth in developing countries regardless of being transitory or permanent

raising primary school enrolment in developing countries the relative importance of supply and demand abstract few policies are as universally accepted as raising primary school enrolment in developing countries but the policy levers for achieving this goal are not straightforward this paper merges household survey data with detailed school supply characteristics from official sources in order to estimate the relative impact of demand and supply side determinants of rural primary school enrolment in mozambique policy simulations based on a set of plausible interventions show that in rural mozambique building more schools or raising adult literacy will have a larger impact on primary school enrolment rates than interventions that raise household income when relative costs are considered adult literacy campaigns are nearly 10 times more cost effective than the income intervention and 1 5 to 2 5 times better than building more schools

the hidden economy as an unobserved variable abstract the technique of unobserved variables is used to estimate the relative size and development time of the hidden economy of oecd countries the burdens of taxation and regulations and the tax morality turn out to be statistically significant determinants at the end of the scandinavian and benc lux countries are expected to have a relatively large and japan and switzerland a relatively small hidden economy canada and the united states are rank in the middle the size of all hidden sectors is estimated to have increased in the period 1960 1973 relative to officially measured gnp

the causality relationship between energy consumption and gdp in g 11 countries revisited abstract this paper explores whether energy conservation policies can be implemented in countries with the same level of development that is is restraining energy consumption without compromising economic growth feasible in all industrialized countries a new granger non causality testing procedure developed by toda and yamamoto 1995 journal of econometrics 66 225 250 is applied to re investigate the relationship if any between energy consumption and income in 11 major industrialized countries the results clearly do not support the view that energy consumption and income are neutral with respect to each other except in the case of the united kingdom germany and sweden where a neutral relationship is found bi directional causality in the united states and uni directional running from energy consumption to gdp in canada belgium the netherlands and switzerland are found this indicates that energy conservation may hinder economic growth in the latter five countries further the causality relationship appears to be uni directional but reversed for france italy and japan which implies that in these three countries energy conservation may be viable without being detrimental to economic growth

energy consumption real income and temporal causality results from a multi country study based on cointegration and error correction modelling techniques abstract unlike previous studies on the causal relationship between energy consumption and economic growth this paper illustrates how the finding of cointegration i e long term equilibrium relationship between these variables may be used in testing granger causality based on the most recent johansen s multivariate cointegration tests preceded by various unit root or non stationarity tests we test for cointegration between total energy consumption and real income of six asian economies india pakistan malaysia singapore indonesia and the philippines non rejection of cointegration between variables rules out granger non causality and imples at least one way of granger causality either unidirectional or bidirectionial secondly by using a dynamic vector error correction model we then analyse the direction of granger causation and hence the within sample granger exogeneity or endogeneity of each of the variables thirdly the relative strength of the causality is gauged through the dynamic variance decomposition technique by decomposing the total impact of an unanticipated shock to each of the variables beyond the sample period into proportions attributable to shocks in the other variables including its own in the bivariate system results based on these tools of methodology indicate that while all pair wise relationships shared common univariate integrational properties only relationships for three countries india pakistan and indonesia were cointegrated for these countries temporal causality results were mixed with unidirectional causality from energy to income for india exactly the reverse for indonesia and mutual causality for pakistan the vdcs were not inconsistent with these results and provided us with an additional insight as to the relatively more dominant direction of causation in pakistan simple bivariate vector autoregressive models for the three non cointegrated systems did not indicate any direction of causality significantly in either direction

energy consumption and gdp causality relationship in g 7 countries and emerging markets abstract the causality relationship between energy consumption and income is a well studied topic in energy economics this paper studies the time series properties of energy consumption and gdp and reexamines the causality relationship between the two series in the top 10 emerging markets excluding china due to lack of data and g 7 countries we discover bi directional causality in argentina causality running from gdp to energy consumption in italy and korea and from energy consumption to gdp in turkey france germany and japan hence energy conservation may harm economic growth in the last four countries

quantifying the black economy measurement without theory yet again i shall argue that measurement without theory is a fair description of the published empirical work aimed at guestimating the size of the hidden or black economy i shall also argue that a mere guestimate of the overall size of the black economy is of limited value for the policy maker it is also important to know who is doing what where how and why then we can see what should and or can be done about legislating for or against the black economy in assessing the various attempts to measure the size of the black economy one should also be aware of a political dimension to some of this work perhaps a large and growing black economy is an indication that the economy is overtaxed and over regulated and a neo liberal adjustment is needed to free it up if a large part of the black economy is social security fraud then maybe unemployment is not really as bad as it looks clearly such political conclusions depended on having good theoretical as well as sound quantitative foundations and both these components were generally missing

the informal sector in developed and less developed countries a literature survey the main goal of this study is two fold 1 to provide ageneral overview of the contributions to the literature on theinformal sector with a special focus on the public choiceapproach and 2 to compare these contributions across twoinstitutionally different types of countries developed andless developed developing and transition countries thepaper focuses on the criteria used to define the informalsector the relationship between the formal and informaleconomy tax evasion and public choice analysis it isstressed throughout this paper that the distinction betweenthe two types of countries is of key importance

school supply constraints and children s educational outcomes in rural ghana abstract studies of school attainment often fail to acknowledge the possibility that prices for all schooling levels affect the decision to attend any one schooling level in developing countries the assumption that schooling costs are constant throughout the education cycle is manifestly untrue this paper concentrates on the empirical implications of introducing schooling costs that increase with schooling level the results suggest that the cost of advanced levels of education influences decisions at the primary school level the relative magnitude of the cross price elasticities suggests that cross price effects should not be ignored when designing educational user fees

energy consumption and economic growth in the next 11 countries the bootstrapped autoregressive metric causality approach abstract departing from previous literature using bootstrapped autoregressive metric causality approach which is more robust against non stationarity and break problems than lag augmented tests this study analyzes causal relation between economic growth and energy consumption in the next 11 countries estimating a trivariate model consisting of gdp per capita energy consumption per capita and gross capital formation it was found that the neutrality hypothesis is valid for all of the countries except for turkey these findings imply that energy conservation oriented policies should be implemented in bangladesh egypt indonesia iran korea mexico pakistan and philippines in the case of turkey a unidirectional causal nexus was found from energy consumption to economic growth since the growth hypothesis is valid energy conservation policy poses an obstacle for economic growth in turkey

education demand and age at school enrollment in tanzania in tanzania actual school enrollment takes place 2 or 3 years later on average than the legal enrollment age in this paper we develop a micro economic model that allows us to disentangle various explanations for such delays we simultaneously estimate enrollment age and schooling duration by maximum likelihood techniques using data from the human resource development survey carried out in tanzania in 1992 93 a particularly interesting result of our econometric analysis is that boys and girls follow fundamentally different patterns of schooling our model suggests that this could be due to different return from pre school training in the family s economic activities or it could be related to the wish to have girls ready to be married as early as possible

an endogenous model of public school expenditures and private school enrollment abstract this paper examines the link between private school enrollment rates and public school expenditures using a panel of new york state school districts models are estimated in which public school spending and private school enrollment rates are endogenously determined the results indicate the presence of endogeneity increases in private school enrollment are not shown to cause decreases in public school per pupil expenditure private school enrollment rates are found to respond to changes in public school expenditure and are sensitive to changes in tuition

estimation of real gdp and unrecorded economy in turkey based on environmental data abstract this paper estimates the real gross domestic product gdp and unrecorded economy for turkey using the kalman filter technique using different tests most of the research articles on energy policy investigate the causal relationship between energy consumption and gdp for different countries on the other hand other studies on climate change try to show the effects of both energy consumption and gdp on carbon dioxide co2 emission since the unreported economy has an important weight in developing countries where the recorded or official gdp suffers from considerable measurement problems investigation of the relationship between the recorded gdp and energy consumption may lead to biased results in this paper the economic variables gdp country population as well as environmental variables co2 emission forest area are used in order to estimate gdp which is an unobserved variable in our model the results clearly indicate that first the true gdp in turkey that our model estimates is higher than the observed recorded gdp in the whole period of observation 1973 2003 and the size of unrecorded economy varies between 12 and 30 percent of the observed gdp second the gap between the true gdp and the observed gdp has an increasing trend third if the change in gdp per primary energy supply is smaller than the change in co2 per primary energy supply then there may exist unrecorded economy

ends against the middle determining public service provision when there are private alternatives abstract public provision of a service coexists with private market provision the quality of public provision is determined by majority vote preferences are not single peaked owing to the presence of private alternatives we identify two cases in one majority voting equilibrium always exists and the median income voter is pivotal in the other a necessary condition for equilibrium indentifies the pivotal voter who must have income below the median when equilibrium exists a coalition of middle income households who consume the public alternative will be opposed by a coalition of rich and poor households with the rich choosing private consumption

the short and long run causality relationship among economic growth energy consumption and financial development evidence from south mediterranean countries smcs abstract this study aims at examining the short run and long run causal link between economic growth energy consumption and financial development by using data set of 6 smcs for the 1995 2015 periods the basic testing procedure requires four steps adf and pp unit root tests bound tests for co integration ardl approach and vecm method the results confirm cointegration between the variables it means that the long run relationship exists the short run causal relationships unidirectional exist at least once for each country except egypt the granger causality results for individual countries give mixed results these results urge for the attention of the policy makers in smcs to design a comprehensive energy conservation policy to minimize the consequences of massive energy consumption on economic growth by adding financial development

a multivariate cointegration analysis of the role of energy in the us macroeconomy abstract this paper extends my previous analysis of the causal relationship of gdp and energy use in the usa in the post war period a majority of the relevant variables are integrated justifying a cointegration analysis the results show that cointegration does occur and that energy input cannot be excluded from the cointegration space the results are plausible in terms of macroeconomic dynamics the results are similar to my previous granger causality results and contradict claims in the literature based on bivariate models that there is no cointegration between energy and output

causal relationship between energy consumption and gdp growth revisited a dynamic panel data approach abstract this paper uses the panel data of energy consumption and gdp for 82 countries from 1972 to 2002 based on the income levels defined by the world bank the data are divided into four categories low income group lower middle income group upper middle income group and high income group we employ the gmm sys approach for the estimation of the panel var model in each of the four groups afterwards the causal relationship between energy consumption and economic growth is tested and ascertained we discover a in the low income group there exists no causal relationship between energy consumption and economic growth b in the middle income groups lower and upper middle income groups economic growth leads energy consumption positively c in the high income group countries economic growth leads energy consumption negatively after further in depth analysis of energy related data the results indicate that in the high income group there is a great environmental improvement as a result of more efficient energy use and reduction in the release of co2 however in the upper middle income group countries after the energy crisis the energy efficiency declines and the release of co2 rises since there is no evidence indicating that energy consumption leads economic growth in any of the four income groups a stronger energy conservation policy should be pursued in all countries

energy consumption and economic growth assessing the evidence from greece abstract this paper attempts to shed light into the empirical relationship between energy consumption and economic growth for greece 1960 1996 employing the vector error correction model estimation the vector specification includes energy consumption real gdp and price developments the latter taken to represent a measure of economic efficiency the empirical evidence suggests that there is a long run relationship between the three variables supporting the endogeneity of energy consumption and real output these findings have important policy implications since the adoption of suitable structural policies aiming at improving economic efficiency can induce energy conservation without impeding economic growth

causality between energy consumption and economic growth in india a note on conflicting results abstract this note examines the different direction of causal relation between energy consumption and economic growth in india applying engle granger cointegration approach combined with the standard granger causality test on indian data for the period 1950 1996 we find that bi directional causality exists between energy consumption and economic growth further we apply johansen multivariate cointegration technique on the different set of variables the same direction of causality exists between energy consumption and economic growth this is different from the results obtained in earlier studies

portfolio choice and pricing in illiquid markets abstract this paper studies portfolio choice and pricing in markets in which immediate trading may be impossible it departs from the literature by removing restrictions on asset holdings and finds that optimal positions depend significantly and naturally on liquidity when expected future liquidity is high agents take more extreme positions given that they do not have to hold those positions for long when they become undesirable consequently larger trades should be observed in markets with more frequent trading liquidity need not affect the price significantly however because liquidity has offsetting impacts on different agents demands this result highlights the importance of unrestricted portfolio choice the paper draws parallels with the transaction cost literature and clarifies the relationship between the price level and the realized trading frequency in this literature

how many times again will we examine the energy income nexus using a limited range of traditional econometric tools during the last three decades following closely the developments in econometric theory energy and environmental economists have empirically examined the energy income nexus for different countries and time periods however today in spite of the growing interest in this area the state of knowledge is still controversial and unsettled this viewpoint paper attempts to highlight some of the issues related to the existing literature on the long run relationship and causality between energy consumption and economic growth in particular it discusses how it is difficult to make policy recommendations on the basis of inconsistent and conflicting results in the published literature on the subject in order to do so the paper first illustrates the increasing trend in the number of studies published in this area providing also a brief comparison of the conventional methods used to estimate the energy income nexus it then deals with new directions and different viewpoints on the same issue

energy consumption and economic growth in vietnam abstract this study attempts to analyse the relationship between energy consumption and economic growth in vietnam using the neoclassical solow growth framework for the 1971 2011 period the concept and methods of cointegration and granger causality are used to establish the relationship between the variables of interest our results confirm the existence of cointegration among the variables in particular energy consumption fdi and capital stock were found positively influence economic growth in vietnam the granger causality test revealed unidirectional causality running from energy consumption to economic growth hence vietnam is an energy dependent economy and any energy or environment policy drawn up in an attempt to conserve energy will jeopardise the process of economic development in vietnam for this reason the renewable energy policy should be given attention to provide sufficient supplies of energy to speed up economic expansion investment in r d may be required to incentivise private public institutions to engage in this innovation while the awareness for energy saving policy among public could be integrated to meet social economic development

accountability and yardstick competition in the public provision of education abstract this paper explores the institutional change introduced by the public disclosure of an education development index ideb basic education development index in 2007 to identify the effect of education accountability on yardstick competition in educational spending among brazilian municipalities an exploratory analysis of the data shows a minor reduction 20 in spatial interaction in public educational spending after ideb disclosure compared with the spatial correlation before disclosure of the index our main results explore a discontinuity around the cutoff of 30 students enrolled in the grade under assessment after ideb disclosure the estimates suggest that the spatial autocorrelation and thus yardstick competition is reduced by 52 falsification and robustness tests were performed and suggest that we can claim causality around small bandwidths of the cutoff this finding suggests that the public release of information may decrease the importance of neighbors information on voters decisions

energy consumption and gdp revisited a panel analysis of developed and developing countries this paper applies a new panel data stationarity testing procedure first developed by carrion i silvestre et al 2005 econometrics journal 8 159 175 with panel vars that employ the generalized method of moment techniques in order to re investigate the dynamic interactions between energy consumption per capita lec and real gdp per capita lry in 22 developed and 18 developing countries when multiple breaks in the series are taken into account there is convincing evidence of panel stationarity for lec and lry in both groups the energy crises evidently had a substantive impact on both lec and lry in all sample countries furthermore our panel vars attest to bidirectional causality between lec and lry in developed countries but there is uni directional causality from lry to lec in developing countries finally from the orthogonalized impulse response functions all of the variables in the panel vars have a positive effect on each other but their impact is greater and more persistent in developing countries some important policy implications do emerge

the demand for primary schooling in madagascar price quality and the choice between public and private providers abstract we estimate a discrete choice model of primary schooling and simulate policy alternatives for rural madagascar among school quality factors the results highlight the negative impacts on schooling demand of poor facility quality and the use of multigrade teaching several grades being taught simultaneously by one teacher in public schools simulations indicate the feasibility of reducing multigrade in public schools by adding teachers and classrooms a policy that would lead to modest improvements in overall enrollments and would disproportionately benefit poor children given much higher price elasticities for poorer households raising school fees to cover some of the additional costs would strongly counteract these favorable distributional outcomes an alternative policy of consolidation of primary schools combined with multigrade reduction or other quality improvements is likely to be ineffective because of the strongly negative impact of distance to school

industrial electricity demand for turkey a structural time series analysis abstract this research investigates the relationship between turkish industrial electricity consumption industrial value added and electricity prices in order to forecast future turkish industrial electricity demand to achieve this an industrial electricity demand function for turkey is estimated by applying the structural time series technique to annual data over the period 1960 to 2008 in addition to identifying the size and significance of the price and industrial value added output elasticities this technique also uncovers the electricity underlying energy demand trend uedt for the turkish industrial sector and is as far as is known the first attempt to do this the results suggest that output and real electricity prices and a uedt all have an important role to play in driving turkish industrial electricity demand consequently they should all be incorporated when modelling turkish industrial electricity demand and the estimated uedt should arguably be considered in future energy policy decisions concerning the turkish electricity industry the output and price elasticities are estimated to be 0 15 and 0 16 respectively with an increasing but at a decreasing rate uedt and based on the estimated equation and different forecast assumptions it is predicted that turkish industrial electricity demand will be somewhere between 97 and 148 twh by 2020

sectoral energy consumption by source and economic growth in turkey this paper provides a detailed analysis of the energy consumption in turkey during the last 40 years it investigates the causal relationships between income and energy consumption in two ways first the relationship is studied at the aggregate level then we focus on the industrial sector previous findings suggest that in the case of turkey there is a unidirectional causality running from energy consumption to growth however our findings suggest that in the long run income and energy consumption appear to be neutral with respect to each other both at the aggregate and at the industrial level we also find a strong evidence of instantaneous causality which means that contemporaneous values of energy consumption and income are correlated furthermore a descriptive analysis is conducted in order to reveal the differences in the use of energy resources we conclude that energy conservation policies are necessary for environmental concerns and our empirical results imply that such policies would not impede economic growth in the long term

public education expenditures and private school enrollment in this paper i investigate whether increases in public education expenditures lead to reductions in private school enrollment in order to deal with the endogeneity of public expenditures i use as a natural experiment the 1998 fundef reform in brazil that caused exogenous variations in local public school funding using data from brazilian school and population censuses i show that public education expenditures increases are associated with reductions in the share of private school enrollment for grade 1 however the effect is smaller for grades 2 to 4 which is consistent with the existence of costs associated with switching schools resume depenses pour l instruction publique et inscriptions dans les ecoles privees dans ce memoire on fait enquete pour etablir si des accroissements dans les depenses pour l instruction publique menent a des reductions dans les inscriptions dans les ecoles privees conscient de l endogeneite des depenses publiques l auteur utilise la reforme fundef de 1998 au brazil qui a entraine des variations exogenes dans le financement des ecoles publiques locales a partir des donnees des recensements bresiliens des ecoles et de la population on montre que les accroissements de depenses pour l instruction publique sont associes a des reductions dans la part des ecoles privees dans les inscriptions en premiere annee cependant l effet est plus faible pour les inscriptions dans les annees 2 a 4 qui suivent ce qui est coherent avec l existence de couts associes aux changements d ecole

structural break unit root and the causality between energy consumption and gdp in turkey abstract this paper tries to investigate a series of unit root and causality tests to detect causality between the gdp and energy consumption in turkey employing hsiao s version of granger causality method for the 1950 2000 period the conventional unit root tests indicate the series are i 1 whereas the endogenous break unit root tests proposed by zivot and andrews zivot e and andrews d w k 1992 further evidence on the great crash the oil price shock and the unit root hypothesis journal of business and economics statistics 10 251 270 and perron perron p 1997 further evidence on breaking trend functions in macroeconomic variables journal of econometrics 80 355 385 reveal that the series are trend stationary with a structural break therefore it is inappropriate to take the first difference of the data to achieve stationarity the main conclusion of this study is that there is no evidence of causality between energy consumption and gdp in turkey based on the detrended data

the relationship between energy consumption energy prices and economic growth time series evidence from asian developing countries this paper estimates the causal relationships between energy consumption and income for india indonesia the philippines and thailand using cointegration and error correction modelling techniques the results indicate that in the short run unidirectional granger causality runs from energy to income for india and indonesia while bidirectional granger causality runs from energy to income for thailand and the philippines in the case of thailand and the philippines energy income and prices are mutually causal the study results do not support the view that energy and income are neutral with respect to each other with the exception of indonesia and india where neutrality is observed in the short run c 2000 elsevier science b v all rights reserved jel classifications c22 q43 q48

defining and estimating underground and informal economies the new institutional economics approach abstract a taxonomy of underground economies is elaborated based on the new institutional approach to economic development members of formal sectors confront different sets of transformation and transaction costs than do members of informal sectors and these differences are regarded as crucial to the development process the paper distinguishes illegal unreported unrecorded and informal economies and examines the conceptual and empirical linkages among them alternative micro and macro methodologies for measuring underground activities are reviewed and evaluated including census and survey procedures discrepancy and monetary methods when you cannot measure your knowledge is meager and unsatisfactory lord kelvin inscription at harper library university of chicago

energy consumption and gdp in turkey is there a co integration relationship energy consumption and gdp are expected to grow by 5 9 and 7 annually until 2025 in turkey this paper tries to unfold the linkage between energy consumption and gdp by undertaking a co integration analysis for turkey with annual data over the period 1970 2003 the analysis shows that energy consumption and gdp are co integrated this means that there is a possibly bi directional causality relationship between the two we establish that there is a unidirectional causality running from gdp to energy consumption indicating that energy saving would not harm economic growth in turkey in addition we find that energy consumption keeps on growing as long as the economy grows in turkey

co2 emissions energy consumption and output in france abstract this paper examines the dynamic causal relationships between pollutant emissions energy consumption and output for france using cointegration and vector error correction modelling techniques we argue that these variables are strongly inter related and therefore their relationship must be examined using an integrated framework the results provide evidence for the existence of a fairly robust long run relationship between these variables for the period 1960 2000 the causality results support the argument that economic growth exerts a causal influence on growth of energy use and growth of pollution in the long run the results also point to a uni directional causality running from growth of energy use to output growth in the short run

energy consumption economic growth and carbon emissions challenges faced by an eu candidate member abstract this paper investigates the long run granger causality relationship between economic growth carbon dioxide emissions and energy consumption in turkey controlling for gross fixed capital formation and labor the most interesting result is that carbon emissions seem to granger cause energy consumption but the reverse is not true the lack of a long run causal link between income and emissions may be implying that to reduce carbon emissions turkey does not have to forgo economic growth

a literature survey on energy growth nexus abstract this paper provides a survey of the recent progress in the literature of energy consumption economic growth and electricity consumption economic growth causality nexus the survey highlights that most empirical studies focus on either testing the role of energy electricity in stimulating economic growth or examining the direction of causality between these two variables although the positive role of energy on growth has become a stylized fact there are some methodological reservations about the results from these empirical studies a general observation from these studies is that the literature produced conflicting results and there is no consensus neither on the existence nor on the direction of causality between energy consumption electricity consumption and economic growth as a policy implication to avoid from conflicting and unreliable results the authors may use the autoregressive distributed lags bounds test two regime threshold co integration models panel data approach and multivariate models including new variables such as real gross fixed capital formation labor force carbon dioxide emissions population exchange rates interest rates etc thus the authors should focus more on the new approaches and perspectives rather than by employing usual methods based on a set of common variables for different countries and different intervals of time