Table 4.
Estimation results: Driscoll-Kraay [38] standard errors
| Models | 1 | 2 |
|---|---|---|
| Constant | −8.8219 (−5.86)*** | −6.6460 (− 6.57)*** |
| CO2 | 0.0988 (5.67)*** | – |
| NIT | – | 0.0687 (4.13)*** |
| GDP | − 0.0648 (−2.56)** | −0.0757 (− 3.80)*** |
| PHY | − 0.1214 (−5.41)*** | − 0.1302 (− 7.12)*** |
| URB | − 0.1311 (− 2.00)** | − 0.1723 (− 2.30)** |
| WAT | 3.1370 (7.06)*** | 2.4197 (7.68)*** |
| SAN | − 0.4528 (−6.41)*** | − 0.3938 (− 6.28)*** |
| SCH | − 0.1003 (− 3.58)*** | 0.0473 (1.46) |
| within R-squared | 0.4945 | 0.4550 |
| F-statistic | 606.57 | 414.64 |
| Probability | 0.0000 | 0.0000 |
| Number of groups | 19a | 19 |
| Number of observations | 225 | 197 |
Note: *** and ** denote significance level at 1 and 5%, respectively
aJapan does not have the secondary school enrolment data for the studied period, therefore, the statistical software and estimation techniques used in this study exclude Japan from this analysis.