Table 6.
Estimation results of the robustness test.
| Variable | (1) | (2) | (3) | (4) |
|---|---|---|---|---|
| Placebo Test | SO2 as Explained Variable | Excluding 31 Key Cities | All Variables Lag For One Period | |
| LCCP | −0.047 | −0.2449 *** | −0.1321 *** | −0.1145 ** |
| (0.1612) | (0.0900) | (0.0439) | (0.0497) | |
| Control | Yes | Yes | Yes | Yes |
| Cons | −4.545 *** | 4.8123 *** | 3.0562 *** | 3.0519 *** |
| (0.2231) | (0.8963) | (0.4263) | (0.4829) | |
| Time-fixed | Yes | Yes | Yes | Yes |
| City-fixed | Yes | Yes | Yes | Yes |
| R2 | 0.3599 | 0.1279 | 0.3185 | 0.3371 |
Note: ** and *** indicate significance at the 5% and 1% levels respectively. Standard errors are in parentheses.