Variable name | First-Tier and Second-Tier Cities | Other Cities |
GMM | GMM | |
City size | −0.803** | 2.294*** |
(−2.26) | (2.95) | |
Square of City Scale | 0.0531*** | −4.507*** |
(2.64) | (−4.20) | |
Environmental pollution | −43.78** | 2.171 |
(−2.41) | (0.47) | |
Interaction between urban scale and environmental pollution | 8.580** | −13.12 |
(2.04) | (−0.36) | |
Intercept term | 3.841*** | 2.754*** |
(12.46) | (11.97) | |
Control variable | Yes | Yes |
Observation value | 2920 | 3097 |