Table 5.
Panel unit root test with structural breaks
| Variable | - | Bartlett Kernel | Quadratic Kernel | Bootstrap critical values | ||
|---|---|---|---|---|---|---|
| 5 percent | 2.5 percent | 1 percent | ||||
| COPC | Ho | 8.758** | 8.761** | 7.713 | 8.100 | 8.853 |
| He | 5.600*** | 5.673*** | 5.405 | 6.813 | 7.239 | |
| POP | Ho | 18.230* | 18.607* | 17.112 | 17.439 | 18.100 |
| He | 20.329** | 20.670** | 18.794 | 20.200 | 21.014 | |
| GDPPC | Ho | 9.439* | 9.501* | 7.800 | 8.132 | 8.809 |
| He | 8.099* | 8.165* | 5.498 | 6.514 | 7.093 | |
| EI | Ho | 15.655*** | 16.119* | 15.400 | 15.684 | 16.019 |
| He | 16.301*** | 16.718*** | 16.055 | 16.788 | 17.490 | |
| GB | Ho | 7.301** | 7.419** | 6.817 | 7.001 | 7.519 |
| He | 6.839* | 6.909* | 5.480 | 5.947 | 6.384 | |
| GEI | Ho | 7.918* | 7.958* | 6.817 | 7.001 | 8.109 |
| He | 8.304** | 8.694* | 5.483 | 5.911 | 8.897 | |
Note: COPC, POP, GDPPC, EI, GB, and GEI indicate CO2 emissions per capita, population, GDP per capita, energy intensity, issued green bonds, and green energy index, respectively. Ho and He stand for homogeneous and heterogeneous, respectively; *, **, and *** denote the significance at 1%, 2.5%, and 5%, respectively.
Source: Authors’ calculation