Table 5 Results of PSM-DID test.
Variables | AQI | |||
|---|---|---|---|---|
One-to-one nearest-neighbor matching (1) | One-to-one nearest-neighbor matching (2) | The kernel density matching (3) | The kernel density matching (4) | |
the establishment of GFRIs | −5.8209*** (−3.8246) | −4.1947*** (−2.6270) | −6.0348*** (−3.3702) | −4.8378*** (−3.0843) |
Control variables | N | Y | N | Y |
Fixed effect | Y | Y | Y | Y |
Obs | 749 | 749 | 6491 | 6491 |
R2 | 0.5007 | 0.5757 | 0.3824 | 0.5356 |
