The role of economic growth, financial development, globalization, renewable energy and industrialization in reducing environmental degradation in the economic community of West African States

Figures & data

Figure 1. The trend of CO₂ emissions (measured by emissions per capita) in ECOWAS from 1990 to 2019.

Source: Figure created by Author.

Table 1. Descriptive statistics and pairwise correlation matrix.

	lnED	lnEG	lnFD	lnGL	lnRE	lnIND
Mean	−1.294	6.867	2.465	3.786	4.169	3.043
Median	−1.206	6.868	2.529	3.813	4.323	3.093
Maximum	0.119	8.107	4.179	4.114	4.554	3.659
Minimum	−3.108	5.809	0.420	3.246	3.034	1.516
Std. Dev.	0.779	0.580	0.766	0.189	0.371	0.357
Skewness	−0.444	0.190	−0.103	−0.553	−1.397	−1.342
Kurtosis	2.510	2.009	2.738	2.861	4.162	6.141
Jarque-Bera	12.836***	14.086***	1.388	15.537***	114.402***	213.448***
Observations	300	300	300	300	300	300
ED	1
EG	0.801***	1
FD	0.531***	0.468***	1
GL	0.739***	0.594***	0.558***	1
RE	−0.630***	−0.564***	−0.634***	−0.412***	1
IND	0.239***	0.137**	−0.053	0.049	−0.012	1

Note. ***and ** indicates 1% and 5% significance, respectively.

Source: Computed by Author.

Figure 2. Scatter plots of the lower triangular matrix.

Source: Figure created by Author.

Figure 3. Trends of variables employed in the analysis.

Source: Figure created by Author.

Table 2. Cross-sectional dependency test results.

Test	lnED	lnEG	lnFD	lnGL	lnRE	lnIND
Breusch-Pagan LM	757.979***	742.276***	443.557***	1142.536***	595.853***	342.900***
Pesaran scaled LM	75.155***	73.499***	42.012***	115.690***	58.065***	31.401***
Bias-corrected scaled LM	74.982***	73.327***	41.839***	115.518***	57.893***	31.229***
Pesaran CSD	15.714***	25.453***	16.975***	33.763***	22.092***	13.196***

Note. *** indicates 1% significance.

Source: Computed by Author.

Table 3. Outcome of slope coefficient homogeneity test.

Test	Test statistic	p-value
$\tilde{\Delta }$	10.956	0.000
$\tilde{\Delta } \mathit{\text{adj}}.$	13.245	0.000
$\tilde{\Delta }$ (HAC)	−2.715	0.007
$\tilde{\Delta } \mathit{\text{adj}}.$ (HAC)	−3.245	0.001

Note. H₀: slope coefficients are homogenous.

Source: Computed by Author.

Table 4. Panel unit root tests.

	lnED	lnEG	lnFD	lnGL	lnRE	lnIND
Level
Breitung and Das test	3.876	7.466	−0.381	4.411	3.912	−1.855**
CADF test	−1.847	−1.574	−1.321	−1.255	−1.589	−1.761
CIPS test	−1.492	−1.430	−1.726	−1.253	−1.691	−2.438**
1st difference
Breitung and Das test	−7.921***	−6.371***	−7.615***	−6.171***	−8.828***	−8.849***
CADF test	−2.767 ***	−3.752***	−3.169***	−3.004***	−2.456**	−3.250***
CIPS test	−5.100***	−4.104***	−4.399***	−5.083***	−4.882***	−5.825***

Notes: ***, **, and * indicate significance at 1, 5, and 10% levels, respectively.

Source: Computed by Author.

Table 5. Results of panel cointegration tests.

	Statistic	p-value
Panel A: Kao test for cointegration
Modified Dickey-Fuller t	−3.0683	0.0011
Dickey-Fuller t	−3.0617	0.0011
Augmented Dickey-Fuller t	−3.3836	0.0004
Unadjusted modified Dickey-Fuller t	−5.2281	0.000
Unadjusted Dickey-Fuller t	−3.8348	0.0001
Panel B: Pedroni test for cointegration
Modified Phillips–Perron t	3.120	0.001
Phillips–Perron t	−2.169	0.015
Augmented Dickey-Fuller t	−2.487	0.006
Panel C: Westerlund cointegration test
Variance ratio	2.394	0.008

Source: Computed by Author.

Table 6. Regression with Driscoll-Kraay standard errors and average marginal effects.

	Coefficient	std. err	t	P>|t|	dy/dx	std. err	z	P>|z|
lnEG	54.486	16.972	3.21	0.011	54.486	16.972	3.210	0.001
lnEG^2	−7.706	2.468	−3.12	0.012	−7.706	2.468	−3.120	0.002
lnEG^3	0.360	0.118	3.05	0.014	0.360	0.118	3.050	0.002
lnFD	−0.078	0.026	−2.98	0.015	−0.078	0.026	−2.98	0.003
lnGL	0.448	0.149	3.01	0.015	0.448	0.149	3.000	0.003
lnRE	−2.556	0.255	−10.01	0.00	−2.556	0.255	−10.010	0.000
lnIND	0.093	0.038	2.48	0.035	0.093	0.038	2.480	0.013
_cons	−119.718	38.247	−3.13	0.012
R-squared	0.843
Prob > F	0.000

Source: Computed by Author.

Figure 4. N-shaped EKC for the ECOWAS region.

Source: Figure created by Author.

Table 7. U test estimation results.

Benin			Burkina Faso
	Lower bound	Upper bound		Lower bound	Upper bound
Interval	771.076	1153.726	Interval	333.172	716.012
Slope	0.015	−0.003	Slope	0.004	0.005
t-Value	1.122	−0.288	t-value
P > t	0.135	0.388	P > t
Turns^a	1084.249		Turns	−1167.758
Shape^b	U shape		Shape	Monotone
Cabo Verde			Cote d’Ivoire
	Lower bound	Upper bound		Lower bound	Upper bound
Interval	780.689	3318.933	Interval	1507.090	2289.377
Slope	0.001	0.000	Slope	0.0001297	0.001
t-Value			t-Value
P > t			P > t
Turns	4257.042		Turns	1374.362
Shape	Monotone		Shape	Monotone
Ghana			Guinea
	Lower bound	Upper bound		Lower bound	Upper bound
Interval	852.431	1981.636	Interval	547.272	937.703
Slope	0.002	−0.00006	Slope	0.002	0.00106
t-Value	0.536	−0.015	t-value
P > t	0.298	0.494	P > t
Turns	1949.285		Turns	1258.135
Shape	U shape		Shape	Monotone
Nigeria			Senegal
	Lower bound	Upper bound		Lower bound	Upper bound
Interval	1429.012	2679.555	Interval	957.688	1409.971
Slope	−0.001	0.00003	Slope	0.005	−0.00076
t-Value	−0.303	0.011	t-value	0.616	−0.104
P > t	0.382	0.496	P > t	0.271	0.459
Turns	2628.239		Turns	1345.249
Shape	Inverse U shape		Shape	U shape
Sierra Leone			Togo
	Lower bound	Upper bound		Lower bound	Upper bound
Interval	356.295	744.070	Interval	398.027	618.491
Slope	0.002	0.00268	Slope	0.004	−0.00314
t-Value			t-value	0.149	−0.128
P > t			P > t	0.441	0.450
Turns	−865.207		Turns	523.067
Shape	Monotone		Shape	U shape

^a Represents a turning point.

^b Represents the interpretation.

Source: Computed by Author.

Table 8. Outcome of panel quantile analysis.

Quantile	Model	lnEG	lnEG^2	lnEG^3	lnFD	lnGL	lnRE	lnIND
25	Coef	11.660***	−1.512***	0.069***	−0.144***	1.529***	−0.716***	0.305***
		[0.667]	[0.094]	[0.004]	[0.010]	[0.061]	[0.019]	[0.011]
50	Coef	36.2.6***	−4.990***	0.232***	−0.023	1.169***	−0.629***	0.201***
		[12.768]	[1.798]	[0.084]	[0.019]	[0.128]	[0.024]	[0.022]
75	Coef	−20.049***	2.958***	−1.422***	−0.117***	1.181***	−0.571***	0.172***
		[2.444]	[0.349]	[0.017]	[0.025]	[0.098]	[0.055]	[0.050]

Source: Computed by Author.

Availability of data and materials

In this investigation, we exclusively used secondary data from public sources. Therefore, in this study, no new data is used or produced.