Table 3.
Unit root test
| Method | CO2 | D (CO2) | ENC | D(ENC) | TOU | D(TOU) | URB | D(URB) | RGDP | D(RGDP) |
|---|---|---|---|---|---|---|---|---|---|---|
| Null: unit root (assumes common unit root process) | ||||||||||
| Levin, Lin and Chu t* | 1.963 | 0.513 | − 1.46* | − 3.25*** | − 0.257 | − 4.57*** | − 2.96** | 0.805 | − 2.23** | − 3.69*** |
| Breitung t stat | 1.652 | − 2.61*** | 0.454 | − 4.45*** | 1.078 | − 4.28*** | 6.329 | − 3.85*** | − 1.169 | − 3.35*** |
| Null: unit root (assumes individual unit root process) | ||||||||||
| Im, Pesaran and Shin W stat | 1.967 | − 3.56*** | − 0.55 | − 3.49*** | 1.159 | − 4.27*** | − 0.263 | 2.781 | − 1.212 | − 2.43*** |
| ADF—Fisher chi-square | 6.408 | 37.90*** | 18.98 | 36.34*** | 9.716 | 43.53*** | 16.494 | 3.527 | 18.955 | 27.79** |
| PP—Fisher chi-square | 27.78** | 83.91*** | 24.65 | 112.13*** | 7.45 | 72.04*** | 31.49** | 1.368 | 16.786 | 46.51*** |
Panel unit root test: summary
***,** and * represents 1%, 5% and 10% levels of significance