| VARIABLES | (1) | (2) |
| lnoper_cost | ROA | |
| timetreat | 0.0821*** | 0.777** |
| (0.0211) | (0.311) | |
| time | 0.239*** | −6.431*** |
| (0.0429) | (0.419) | |
| treat | −0.325* | 0.184 |
| (0.178) | (0.649) | |
| Constant | 7.380*** | −4.617 |
| (0.500) | (4.598) | |
| 控制变量 | 是 | 是 |
| 时间固定效应 | 是 | 是 |
| 地区固定效应 | 是 | 是 |
| 行业固定效应 | 是 | 是 |
| Observations | 12,464 | 12,464 |