The long-term relationship between renewable energy and ecological footprint is examined in the study's analysis for five selected developing nations in Europe (Czechia, Croatia, Poland, Romania, Romania, and Turkey). The tests are conducted utilising new-generation panel data analysis methods and annual data from 1994 to 2018. The central claim of the study is that "renewable energy sources and ecological footprint have a long-term relationship." In this context, the approach to be utilised is decided upon once the data set and model of the variables to be employed in light of the hypothesis are introduced. The results of the analyses are evaluated once the theoretical and conceptual framework for the tests to be used within the parameters of the procedure is presented.
3.1. The Data Set and Model
Due to a shared data restriction across the variables in the model, the analyses are based on annual data for the years 1994 to 2018. As a result, the five developing European nations of Croatia, Poland, Romania, Romania, and Turkey are chosen as the study's country sample. This group of nations was chosen mostly due to their recent rise to prominence in both European and international trade, strong potential for expansion, and status as the nations receiving the greatest foreign investment following the pandemic. These nations also stand out in the environmental issues brought on by global industry, given their population concentrations and market sizes. The kind and quantity of energy utilised during production phases, as well as the environmental rules they'll put in place, are crucial in today's interconnected world. As a result, the sample of the study is made up of these five nations, who are anticipated to lead the way in future global trade.
Based on studies in the literature, the variables in the model developed to test the hypothesis were chosen. The ecological footprint (EF), which has lately been the most frequently cited environmental indicator in the literature and is regarded as the most thorough because it takes a wide range of environmental issues into account, has been chosen as the dependent variable in this situation. The model includes three independent variables: energy productivity (EP), tax revenue connected to energy (ETR), and consumption of renewable energy (REC). The ecological footprint in the model is affected by the GDP and the development of environment-related technologies (DET), which are chosen as control variables.
All of the model's variables are the most desired variables and do not have widespread data issues, as can be shown from the literature. The most commonly chosen control variable in environmental research, particularly in EKC hypothesis analysis, when these variables are examined, as observed in many studies in the literature, is GDP. Since it is believed that advancements in environmental technologies will have an impact on the ecological footprint, DET, which is chosen as another control variable, is incorporated into the model. In addition, it is not essential to take the variables' logarithms because every variable in the model is composed of proportional expressions. Table 1 lists relevant variables and any necessary descriptions.
Table 1
Variables | Definition of the variable | Resource |
EF | Ecological Footprint | Global Footprint Network |
REC | Renewable energy consumption (% of total final energy consumption) | World Bank |
ETR | Energy related tax revenue | OECD |
EP | Energy productivity (Euro per kilogram of oil equivalent) | World Bank |
DET | Development of environment-related technologies, % all technologies | OECD |
GDP | Growth (annual %) | World Bank |
In the paper examining the relationship between renewable energy and ecological footprint, the model created within the specified sample and data range is constructed as follows within the scope of the hypothesis established.
$${EF}_{it}= {\beta }_{0}+ {\beta }_{1}{REC}_{it}+{{\beta }_{2}ETR}_{it}+ {\beta }_{3 }{EP}_{it}+ {\beta }_{4 }{DET}_{it} + {\beta }_{5 }{GDP}_{it}+ {\epsilon }_{it}$$
1
In the model, i = 1, 2, 3, ....N denotes cross-section data, t = 1, 2, 3, .....T denotes time dimension and ɛ denotes error term. Since all variables in the model are in the form of proportions or indices, they are included in the analyses without taking their logarithms.
3.2. Econometric method
The following methodological steps were used in the study to examine the long-term relationship between renewable energy and ecological footprint over five selected developing countries in Europe: Analysis of graphs and descriptive statistics of variables; Breusch-Pagan's CDlm1 and Pesaran et al.'s LMadj test for analysing the existence of cross-section dependence of variables; and LMadj test for analysing the existence of the relationship between variables and ecological footprint. Fisher ADF, Fisher PP, Im, Pesaran, and Shin (2003) unit root tests, the (PANIC) unit root test developed by Bai and Ng (2004, 2010), Levin, Lin, and Chu (2002), and Levin, Lin, and Chu (2002), Applying the Durbin-Hausman cointegration test created by Westerlund (2008) to assess whether there is a cointegration relationship between variables, the Delta test established by Pesaran and Yagamata (2008) to determine whether the slope coefficients vary between units, The CCE estimator produced by Pesaran (2006) and the AMG estimator developed by Eberhardt and Bond (2009) are used to estimate the cointegration coefficients of the variables. Lastly, the Konya (2006) panel causality test is used to determine whether the relationship between the variables is causal.
3.2.1. Descriptive Statistics and Graphical Analysis of Variables
Before moving on to the analyses in econometric studies, the descriptive statistics for each of the variables in the model should be provided and interpreted independently. In this setting, it is possible to see the changes and cyclical oscillations of the variables between the given years and comment on their statistical changes. The following are the graphical representation and explanations of the variables used to analyse the relationship between renewable energy and ecological footprint over five specifically chosen developing countries in Europe; Analysis of the EF variable reveals that it reached its peak in the Czech Republic in 1994 and reached its lowest point in 2018. Its trajectory has varied in other nations. While Croatia has the greatest REC variable, it is shown that use of renewable energy in Poland and the Czech Republic is still quite low. However, this rate has risen over time in the Czech Republic. It may be claimed that the ETR in Türkiye has been dropping through time, despite the fact that the ETR variable has generally displayed a varying course in all countries. The DET variable generally oscillates near the same mean. It might also be argued that Romania has the lowest and Poland has the highest. Even while the GDP variable changes on average across all nations, it is noted that GDP bottomed out, particularly during times of world crises like 2008. In contrast, the EP variable normally tends to rise across all nations over time. Only in Poland after 2012 can a significant drop be considered to have occurred.
In the study analysing the relationship between renewable energy and ecological footprint, whether the series of variables included in the model are normally distributed or not is interpreted according to the kurtosis and skewness results. In cases where the kurtosis value is greater than 3, it can be said that the series is pointed, and in cases where it is less than 3, it can be said that the series is flattened. Considering the interpretation of skewness result; when the value is equal to zero, it shows normal distribution. A value greater than zero indicates that the series is positively (left) skewed, while a value less than zero indicates that the series is negatively (right) skewed (Kapusuzoğlu & Karan, 2010: 61–62).
Table 2
Descriptive Statistics of Variables
| Observation | Mean | Max | Min | Standard deviation | Skewness | Kurtosis | Jarque-Bera |
EF | 125 | 3.820948 | 7.179046 | 2.130336 | 1.140558 | 0.574492 | 2.387543 | 8.829514 ( 0.012097) |
REC | 125 | 14.4 | 34.1265 | 5.241574 | 8.143925 | 0.499084 | 2.110726 | 9.308075 (0.009523) |
ETR | 125 | 82.76794 | 99.92476 | 64.30836 | 7.822924 | -0.18616 | 2.616712 | 1.487153 (0.475411) |
DET | 125 | 9.99 | 28.85 | 0.000 | 4.771218 | 0.870448 | 4.62516 | 29.54095 (0.000000) |
GDP | 125 | 4.001029 | 11.20011 | -7.3 | 3.551555 | -0.76746 | 3.646024 | 14.44436 (0.00073) |
EP | 125 | 4.808000 | 7.532000 | 1.793000 | 1.529177 | -0.06108 | 1.966029 | 5.645954 (0.059439) |
Note: Values in brackets indicate probability values. |
According to the results of Table 2, since the skewness values of EF, REC and DET variables are greater than zero, the series are left skewed, while the values of other variables are right skewed since they are less than zero. In kurtosis values, since the values of DET and GDP variables are greater than 3, the series are pointed, and since the values of other variables are less than 3, the series are flattened.
3.2.2. Cross-Section Dependency Test
Prior to conducting hypothesis testing in research using panel data analysis, it is required to ascertain whether there is a cross-sectional relationship between the variables. The interdependence of nations grows as the globe becomes more globalised every day. As a result of this interdependent mechanism, positive or negative shocks in one country may have an impact on another. Due to the common factor problem, it is important to know the cross-sectional dependency of variables in econometric investigations When the time dimension is larger than the cross-section dimension (T > N), the Breusch-Pagan (1980) CDlm1 test is used to detect cross-section dependence. When the time dimension is equal to the cross-section dimension (T = N), the Pesaran (2004) CDlm2 test is used to detect cross-section dependence. Finally, when the time dimension is both smaller (TN) and larger (T > N) than the cross-section dimension, the Pesaran (2004) C Five countries make up the nation group analysed in the research. Consequently, N = 5 is the cross-sectional dimension. Since the years between 1994 and 2018 are being examined, the time dimension is 25 (T = 29). As a result, the observation dimension is smaller than the temporal dimension. Both the CDlm1 test by Breusch-Pagan (1980) and the LMadj test by Pesaran et al. (2008) are employed in the analyses since T > N.
Table 3
The Cross-Section Dependency Test Results
Variables | CD Tests | CDlm1 (BP, 1980) | CDlm2 (Pesaran, 2004) | CD (Pesaran, 2004) | LMadj (Pesaran vd., 2008) |
EF | T statistics | 36.82112* | 5.997384* | 5.364479* | 5.893217* |
Probability Value | 0.0001 | 0.0000 | 0.0000 | 0.0000 |
REC | T statistics | 124.4677* | 25.59575* | 2.293544** | 25.49158* |
Probability Value | 0.0000 | 0.0000 | 0.0218 | 0.0000 |
DET | T statistics | 14.08900 | 0.914327 | -0.243959 | 0.810160 |
Probability Value | 0.1690 | 0.3605 | 0.8073 | 0.4178 |
ETR | T statistics | 49.66108* | 8.868487* | -0.335209 | 8.764321* |
Probability Value | 0.0000 | 0.0000 | 0.7375 | 0.0000 |
GDP | T statistics | 52.20904* | 9.438229* | 6.686337** | 9.334062* |
Probability Value | 0.0000 | 0.0000 | 0.0218 | 0.0000 |
EP | T statistics | 180.5146* | 38.12822* | 13.34153* | 38.02405* |
Probability Value | 0.0000 | 0.0000 | 0.0000 | 0.0000 |
Note: *, ** and *** indicates that there is dependence between cross-sections at 1%, 5% and 10% significance level, respectively. |
When Table 3, which shows the cross-section dependence test results, is analysed, it is seen that the probability values of all variables except the DET variable are statistically significant at the 1% level. Accordingly, for all variables, the null hypothesis “there is no cross-sectional dependence” is rejected and the hypothesis “there is cross-sectional dependence among countries” in the panel data is accepted. This situation is also compatible with today’s global world, and it is concluded that a shock to one of the selected 5 country groups will also affect other countries. For this reason, the authorities and decision makers of the countries in the sample included in the analysis should steer the future by taking into account the current situation. The probability value of the DET variable is statistically insignificant according to the LMadj test results. In other words, there is no cross-section dependence for the DET variable.
3.2.3. Panel Unit Root Test Results
In econometric analyses, stationarity tests are required to solve the problem of spurious regression. Granger and Newbold (1974) state that if there is a unit root in the series of the variables included in the model, the results obtained from the analyses will not be actual findings. The main issue to be considered in the stationarity tests of panel data analyses is whether the countries in the sample included in the model are independent of each other. In this context, unit root tests of panel data analyses consist of first- and second-generation tests. While the first generation of unit root tests do not take cross-section dependence into account, the second-generation tests perform their analyses according to cross-section dependence. In today’s global world, it is more realistic that a shock to one of the countries that make up the panel will also affect other countries, and the use of second-generation tests used in the literature is therefore interpreted as a more realistic approach. Since cross-sectional dependence is observed among the variables included in the model, PANIC unit root test, one of the second-generation unit root tests, is used for all variables.
This test, developed by Bai and Ng (2004, 2010), analyses the stationarity of residuals and factors separately. This test is known in the literature as panel analysis of stationarity of residuals and common factors (PANIC). The data generating process is as follows for variable X:
$${X}_{it}= {D}_{it}+{\lambda {\prime }}_{i}{F}_{t}+ {e}_{it}$$
2
The variable Xit is the sum of the common factor and the residuals. The variable Ft is used to eliminate the cross-sectional dependence problem. Factor estimates are obtained by applying the principal components method to the first differenced data. Consistent estimation of factors regardless of whether the residuals are stationary or not does not require the residuals to be stationary. The advantage of this test is that it tests for the presence of a unit root in the residuals when the unit root in the factors is rejected.
For the stationarity of the residuals, Pa and Pb PANIC test statistics and are used. It is constructed from the p-values of the ADF test statistics that investigate the stationarity of eit individually. Pa shows the results of the ADF test with constant and Pb shows the results of the ADF test with constant and trend. In addition, Stock (1990) developed the panel adjusted Sargan and Bhargava (PMSB) test for the autocorrelated eit case. If any of the Pa, Pb and PMSB statistics are unit rooted, it is concluded that the variable is unit rooted.
Table 4
PANIC Unit Root Test Results
Variables | Statistical values | Constant Model | Constant-Trend Model |
Pa | Pb | PSMB | Pa | Pb | PSMB |
EF | T statistics | -0.29 | -0.339 | 0.735 | 1.014 | 1.368 | 1.827 |
Probability Value | 0.386 | 0.3671 | 0.7689 | 0.8447 | 0.9144 | 0.9662 |
∆EF | T statistics | -8.457* | -3.412* | -1.354*** | -10.151* | -5.164* | -1.61*** |
Probability Value | 0.0000 | 0.0003 | 0.0878 | 0.0000 | 0.0000 | 0.0537 |
REC | T statistics | 1.211 | 1.528 | 1.195 | -0.814 | -0.7 | -0.507 |
Probability Value | 0.8871 | 0.9368 | 0.8839 | 0.2079 | 0.242 | 0.3061 |
∆REC | T statistics | -6.761* | -2.893* | -1.285*** | -4.943* | -2.816* | -1.637*** |
Probability Value | 0.0000 | 0.0019 | 0.0974 | 0.0000 | 0.0024 | 0.0642 |
ETR | T statistics | 0.055 | 0.062 | 0.59 | -0.063 | -0.062 | -0.034 |
Probability Value | 0.5219 | 0.5246 | 0.7224 | 0.4749 | 0.4751 | 0.4864 |
∆ETR | T statistics | -12.88* | -4.483* | -1.312*** | -7.626* | -3.998* | -1.376*** |
Probability Value | 0.0000 | 0.0000 | 0.0947 | 0.0000 | 0.0000 | 0.0845 |
GDP | T statistics | -1.67** | -1.258 | -0.592 | -1.014 | -0.853 | -0.551 |
Probability Value | 0.0474 | 0.1042 | 0.277 | 0.1554 | 0.1969 | 0.2909 |
∆GDP | T statistics | -12.633* | -3.825* | -1.624*** | -12.058* | -5.825* | -1.383*** |
Probability Value | 0.0000 | 0.0001 | 0.0854 | 0.0000 | 0.0000 | 0.0834 |
EP | T statistics | -2.567* | -1.292*** | -0.0898 | -1.082 | -0.916 | -0.59 |
Probability Value | 0.0051 | 0.0982 | 0.1846 | 0.1397 | 0.1798 | 0.2776 |
∆EP | T statistics | -4.983* | -2.668* | -1.772*** | -2.811* | -1.839** | -1.947*** |
Probability Value | 0.0000 | 0.0038 | 0.0806 | 0.0025 | 0.033 | 0.0917 |
Note: *, ** and *** indicates that there is dependence between cross-sections at 1%, 5% and 10% significance level, respectively. |
In PANIC unit root test results, all three probability values Pa, Pb and PSMB should be statistically significant. If one of the statistical values is not significant, it is interpreted that the variable has a unit root. In this context, it is seen that all variables included in the model have unit roots in both constant and constant-trend models, and the variables become stationary when the difference is taken (Table 4).
Since there is no cross-section dependence in the DET variable included in the model, its stationarity is analysed with first-generation unit root tests (Im, Peseran and Shin, Levin, Lin & Chu, Fisher ADF and Fisher PP). In these tests, a probability value close to 0 means that the series are stationary, while a probability value close to 1 means that there is a unit root in the series. Table 5 shows the unit root test results for DET variable in constant and constant-trend models. According to the results, DET variable is stationary at 1% significance level in all tests.
Table 5
DET Variable Unit Root Test
Tests | Constant | Constant-trend |
Test Statistic | Probability value | Test Statistic | Probability value |
Im, Peseran&Shin | -5.05296* | 0.0000 | -3.590957* | 0.0002 |
Levin, Lin&Chu | -5.43430* | 0.0000 | -3.79298* | 0.0001 |
Fisher ADF-Chi-square | 44.8037* | 0.0000 | 31.5741* | 0.0005 |
Fisher PP-Chi-square | 54.8229* | 0.0000 | 48.6643* | 0.0000 |
Note: *, ** and *** indicates that there is dependence between cross-sections at 1%, 5% and 10% significance level, respectively. |
The stationarity analysis results in Table 5 can be interpreted as the shock to one of the countries included in the model creates permanent results and does not lose its effect immediately. Moreover, non-stationarity of the series provides the necessary precondition for cointegration tests. When the same test is repeated by taking the first order difference of all series for the stationarity of the series, it is concluded that the variables become stationary at I(I) level. DET variable is stationary at I(0) level.
In the Durbin-Hausman cointegration test, which is the cointegration test to be used in the next section of the study, the dependent variable being I(I) indicates that the sufficient condition for the analysis is met.
3.2.4. Homogeneity Test
In panel data analysis methods, it has to be decided whether the coefficients of the variables assumed to have a long-run cointegration relationship are homogeneous or not. The homogeneity test tests whether the change in one of the countries affects the other countries at the same level. In this context, coefficients are expected to be heterogeneous in models constructed for countries with different economic structures, whereas coefficients are expected to be homogeneous in models constructed for country groups with similar economic structures. In this paper, Slope Homogeneity Test (Delta test) developed by Pesaran and Yagamata (2008) is used to test homogeneity. Delta test is valid for large samples and Delta adj. test is valid for small samples. In the homogeneity test, the null hypothesis (H0) is interpreted as “slope coefficients are homogeneous” and the alternative hypothesis (H1) is interpreted as “slope coefficients are heterogeneous”.
The homogeneity test results of the variables included in the model in the study analysing the relationship between renewable energy and ecological footprint are given in Table 6.
Table 6
Test Statistic | Statistic Value | Probability Value |
Delta tilde | 4.117* | 0.000 |
Delta tilde adj. | 4.816* | 0.000 |
Note: *, ** and *** indicates that there is dependence between cross-sections at 1%, 5% and 10% significance level, respectively. |
According to the homogeneity test results in Table 6, the H0 hypothesis based on the homogeneity of the coefficients in the Delta test is rejected at 1% significance level, and it is decided that the coefficients are heterogeneous. This situation reveals that the effect of a change in the variables included in the model on the ecological footprint differs from country to country.
3.2.5. Durbin-Hausman Cointegration Test Results
The cointegration connection should be checked for the presence of a long-run relationship after the stationarity of the variables has been established. The approaches most commonly employed in the literature—namely, those of Pedroni (1999), Pedroni (2007), Westerlund (2008), and Westerlund and Edgerton (2007)—are used to examine whether a long-run association exists in panel data analysis. Cross-section dependence must be included in cointegration analyses, just as it is in unit root tests. Otherwise, issues could arise, such as embracing the idea that there is a cointegration link even while there isn't one. This issue led Westerlund (2008) to develop the Durbin-Hausman analysis, which is used in this study and takes into account cross-section dependence.
The Durbin-Hausman (DH) test created by Westerlund (2008) was chosen for this investigation for a variety of reasons. The test's second-generation panel cointegration design, which takes into consideration cross-sectional dependence, is by far its most significant advantage. The dependent variable must be I(I), but the independent variables may be I(0) or I(I) (Westerlund, 2008: 205). In addition to this, the Durbin-Hausman cointegration test permits the panel's parameters to be both the same (homogeneous) across units and different (heterogeneous). If the parameters are homogeneous across units, the DH Panel test statistic is utilised, and if they are heterogeneous, the DH Group test statistic. According to the findings of the Delta test devised by Pesaran and Yamagata (2008), it is concluded that the coefficients are diverse in the study examining the relationship between renewable energy and ecological footprint. Therefore, it can be said that the findings of the DH Group test statistic give more trustworthy results for the cointegration test.The cointegration connection can be examined separately in the panel dimension and in the group dimension using the Durbin-Hausman approach. The autoregressive parameter may vary across cross-sections in the DH group test. A cointegration connection may occur in some cross-sections if the H_0 hypothesis is rejected, according to this test. This test makes the assumption that the autoregressive parameter is constant throughout all cross-sections. This presumption states that cointegration relationship is considered to exist for all cross-sections when the H_0 hypothesis is rejected (Di Iorio and Fachin, 2007). Within the parameters of this test, the relationship between renewable energy and ecological footprint is examined. The findings are presented in Table 7.
Table 7
Durbin-Hausman Cointegration Test Results
Test Statistic | Statistic Value | Probability Value |
Durbin-H Group Statistic | 7.835* | 0.000 |
Durbin-H Panel Statistic | 16.479* | 0.000 |
Note: *, ** and *** indicates that there is dependence between cross-sections at 1%, 5% and 10% significance level, respectively. |
Since it is determined that it would be more appropriate to use group statistics in the study according to the result that the slope coefficients change and the variables are heterogeneous in Table 7, the results of Durbin-H Group statistics are taken into consideration. When the probability values of the Durbin-H Panel statistic are analysed, it is concluded that there is a long-term relationship between the variables since it is less than 0.05. Therefore, it is concluded that there is a long-term relationship between renewable energy and ecological footprint in the model.
The detection of long-run relationships between the variables indicates that the necessary precondition for coefficient estimation is met. After the cointegration relationship between two variables is detected, Common Correlated Effects estimators developed by Pesaran (2006) and AMG estimators developed by Eberhardt and Teal (2010) are used to estimate cointegration coefficients.
The Monte Carlo study by Pesaran (2006) shows that cross-section dependence should be tested in panel data models and methods that take this into account, if any, should be used. The Common Correlated Effects (CCE) estimator is an estimator that takes into account the dependence between the cross-sections forming the panel and is developed by Pesaran (2006) (Nazlıoğlu, 2010: 101). CCE long-run coefficient estimators assume that the independent variables and unobserved common effects are stationary and exogenous. It is also consistent when the independent variables and unobserved common effects are stationary (I(0)), first order integrated (I(1)) and/or cointegrated (Nazlıoğlu, 2010:101).
Eberhardt and Bond (2009), Eberhard and Teal (2011), Eberhard (2012) developed the Augmented Mean Group (AMG) estimator, which consider cross-sectional dependence. The AMG estimator takes into account the differences in observable and unobservable factors between panel groups as well as time series characteristics. Eberhardt and Bond (2009) and Eberhard (2012) developed an estimator that can calculate cointegration coefficients for the countries forming the panel and the overall panel with the AMG test. In this method, it takes into account the common factors in the series and is also used in the presence of endogeneity problem, which indicates that there is a correlation between explanatory variables and error terms (Eberhardt and Bond, 2009). AMG estimators with cross-sectional group specification are calculated by averaging the coefficients of each country in the panel. This test is also more powerful than other coefficient estimation methods as it estimates the arithmetic mean of the cointegration coefficients by weighting. The results of AMG and CCE tests are shown in Table 8.
Table 8
Panel Cointegration Coefficients Estimation Results
Independent variables | CCE estimator | AMG estimator |
Coefficient | Standard Error | Probability Value | Coefficient | Standard Error | Probability Value |
REC | -0.6521 | 0.0624 | 0.297 | -0.0514 | 0.0404 | 0.204 |
DET | 0.0084 | 0.0080 | 0.293 | 0.0047 | 0.0074 | 0.522 |
ETR | 0.0279 | 0.0119 | 0.020** | 0.0131 | 0.0085 | 0.124 |
GDP | 0.0175 | 0.0104 | 0.092*** | 0.214 | 0.0080 | 0.007* |
EP | 0.0396 | 0.1655 | 0.811 | -0.2308 | 0.1340 | 0.085*** |
According to the CCE estimator analysis, the coefficient of the ETR variable is significant at the 5% level and the coefficient of the GDP variable is significant at the 10% level. Based on this result, it can be said that there is a positive relationship between ETR and GDP variables and EF. This result is consistent with the theory. Because many studies in the literature have proved that there is a positive relationship between GDP and EF within the scope of the EKC hypothesis. The same is true between tax revenue in the energy sector and EF. Therefore, the positive coefficients of the two variables are within the expectations. The coefficients of other variables are statistically insignificant.
According to the AMG estimator analysis, the coefficient of the GDP variable is significant at the 1% level and the coefficient of the EP variable is significant at the 10% level. Based on this result, it can be said that there is a positive relationship between GDP and EP variables and EF. This result is also consistent with the theory. An explanation about GDP has been made above. Similar processes are also valid for EP. It is known that improvement in energy efficiency will also have a positive effect on EF. Therefore, the positive coefficients of these two variables are within expectations. The coefficients of other variables are statistically insignificant.
3.2.6. Kónya Causality Test
Kónya (2006) developed this test that investigates the existence of causal relationships between variables by using the Seemingly Unrelated Regressions (SUR) estimator introduced to the literature by Zellner (1962). One of the advantages of this test is that since the panel is assumed to be heterogeneous, causality tests can be applied separately for the countries belonging to the panel. Another important advantage of this test is that there is no need to apply unit root and cointegration tests since country-specific critical values are generated. Suppose the Wald statistic calculated for each country after applying the previous test is greater than the critical values at the significance level. In that case, the null hypothesis, "there is no causality between the variables," is rejected. In other words, when the Wald statistic is greater than the critical value, it is concluded that there is causality between the variables.
Table 9
Kónya Causality Results Between EF and ETR
Countries | H0 : ETREF | H0 : EFETR |
| Critical values | | Critical values |
Wald Statistics | %1 | %5 | %10 | Wald Statistics | %1 | %5 | %10 |
Czechia | 1.844 | 8.369 | 4.577 | 3.412 | 1.191 | 9.297 | 4.889 | 3.567 |
Croatia | 0.485 | 12.347 | 6.354 | 4.486 | 2.775 | 11.835 | 6.423 | 4.657 |
Poland | 2.332 | 10.933 | 6.212 | 3.957 | 2.157 | 13.29 | 6.706 | 4.22 |
Romania | 0.113 | 11.907 | 6.472 | 4.611 | 0.005 | 12.47 | 6.5 | 4.274 |
Türkiye | 1.685 | 11.338 | 7.656 | 6.036 | 0.114 | 19.031 | 6.706 | 4.063 |
Note: *, ** and *** indicates that there is dependence between cross-sections at 1%, 5% and 10% significance level, respectively. |
According to the causality analysis results between energy tax revenue and ecological footprint in Table 9, no causality relationship is detected between the variables in any country.
Table 10
Kónya Causality Results Between EF and DET
Countries | H0 : DETEF | H0 : EFDET |
| Critical values | | Critical values |
Wald Statistics | %1 | %5 | %10 | Wald Statistics | %1 | %5 | %10 |
Czechia | 0.542 | 12.914 | 5.548 | 3.817 | 0.21 | 11.737 | 6.326 | 4.475 |
Croatia | 0.001 | 10.243 | 5.722 | 4.328 | 0.038 | 14.162 | 8.665 | 5.706 |
Poland | 0.74 | 9.535 | 5.148 | 3.834 | 2.224 | 9.274 | 4.658 | 3.472 |
Romania | 0.013 | 11.889 | 6.495 | 4.5 | 0.000 | 9.966 | 5.561 | 4.029 |
Türkiye | 4.697*** | 11.053 | 6.029 | 4.257 | 1.113 | 12.678 | 6.581 | 4.203 |
Note: *, ** and *** indicates that there is dependence between cross-sections at 1%, 5% and 10% significance level, respectively. |
In Table 10, only in Türkiye, a unidirectional causality relationship is detected from environmental technologies to ecological footprint at 10% level. No causality relationship is detected between other variables. Based on this result, it can be concluded that the technology-intensive production structure in Türkiye may be effective on ecological footprint.
Table 11
Kónya Causality Results Between EF and GDP
Countries | H0 : GDPOF | H0 : EFGDP |
| Critical values | | Critical values |
Wald Statistics | %1 | %5 | %10 | Wald Statistics | %1 | %5 | %10 |
Czechia | 0.637 | 9.693 | 5.219 | 3.914 | 6.411*** | 16.419 | 7.788 | 4.887 |
Croatia | 0.034 | 12.718 | 6.175 | 4.29 | 0.628 | 14.081 | 8.574 | 5.954 |
Poland | 0.195 | 11.449 | 7.041 | 4.663 | 0.174 | 13.129 | 7.387 | 4.976 |
Romania | 2.543 | 13.093 | 6.754 | 4.415 | 5.699*** | 13.967 | 7.626 | 4.865 |
Türkiye | 2.069 | 8.686 | 5.114 | 3.356 | 11.872** | 13.55 | 6.564 | 4.238 |
Note: *, ** and *** indicates that there is dependence between cross-sections at 1%, 5% and 10% significance level, respectively. |
Table 11 shows a unidirectional causality relationship from ecological footprint to GDP at 10% level in Czechia and Romania and at 5% level in Türkiye. It is concluded that ecological footprint is effective with the production dimension in the mentioned countries, and that the reduction of environmental problems can be effective in production and national income by creating an exogenous effect.
Table 12
Kónya Causality Results Between EF and EP
Countries | H0 : EPOF | H0 : EFEP |
| Critical values | | Critical values |
Wald Statistics | %1 | %5 | %10 | Wald Statistics | %1 | %5 | %10 |
Czechia | 0.067 | 10.85 | 6.146 | 4.344 | 0.047 | 15.693 | 7.502 | 4.214 |
Croatia | 0.367 | 10.92 | 6.984 | 4.57 | 0.534 | 11.725 | 7.146 | 4.485 |
Poland | 0.021 | 10.581 | 6.068 | 4.206 | 1.061 | 12.29 | 6.295 | 3.785 |
Romania | 3.116 | 11.866 | 6.661 | 4.496 | 0.008 | 12.357 | 6.404 | 4.533 |
Türkiye | 0.074 | 6.507 | 3.862 | 2.647 | 0.169 | 5.242 | 3.107 | 2.156 |
Note: *, **, and *** indicate dependence between cross-sections at 1%, 5%, and 10% significance levels, respectively. |
According to the causality analysis results between energy efficiency and ecological footprint in Table 12, no causality relationship is detected between the variables in any country.