Table 2.
Unit-root test results.
| Variables | DF-GLS unit-root test |
Zivot-Andrews unit-root test |
Order of Integration | |||
|---|---|---|---|---|---|---|
| Intercept | Intercept + trend | break in trend | Break in intercept + trend | |||
| ln CO2 | I(0) | 1.203 | -2.232 | -3.172 | -3.961 | I(1) |
| I(1) | -6.338∗ | -5.293∗ | -6.537∗ | -6.559∗ | ||
| ln CH4 | I(0) | 2.279 | -1.117 | -4.631∗∗ | -5.999∗ | I(1)a |
| I(1) | -6.541∗ | -6.195∗ | - | - | ||
| ln N2O | I(0) | 1.524 | -1.826 | -4.316∗∗ | -4.421 | I(1) |
| I(1) | -7.498∗ | -6.325∗ | -7.798∗ | -7.949∗ | ||
| ln RGDP | I(0) | 3.823 | 0.17 | -0.958 | -0.954 | I(1) |
| I(1) | -5.254∗ | -6.837∗ | -8.354∗ | -8.621∗ | ||
| ln Ind-ratio | I(0) | 2.432 | -1.741 | -1.770 | -2.579 | I(1) |
| I(1) | -4.132∗ | -4.696∗ | -7.782∗ | -7.803∗ | ||
| (ln Ind-ratio)2 | I(0) | -0.21 | -2.00 | -3.040 | -2.937 | I(1) |
| I(1) | -3.727∗ | -4.256∗ | -5.429∗ | -5.954∗ | ||
| ln GNDI | I(0) | 2.022 | 0.083 | -1.737 | -1.713 | I(1) |
| I(1) | -5.023∗ | -7.052∗ | -7.974∗ | -8.420∗ | ||
| (ln GNDI)2 | I(0) | 2.09 | 0.128 | -1.728 | -1.702 | I(1) |
| I(1) | -5.078∗ | -7.005∗ | -8.233∗ | -8.765∗ | ||
| ln FEC | I(0) | 0.060 | -2.498 | -3.614 | -4.905∗∗∗ | I(1) |
| I(1) | -4.921∗ | -5.215∗ | -6.266∗ | -6.405∗ | ||
Note: ∗ denote statistical significance at 1 % level. I(0) and I(1) represent at levels and first differences respectively. ‘a’ indicates that the I(0) variables in the Zivot-Andrews test results.