| Variable | lnCost | lnCost | lnCost | lnCost | 
| (1) SOEs | (2) non-SOEs | (3) SOEs | (4) non-SOEs | |
| constant | 0.015 | −0.025 | 0.015 | −0.025 | 
| (1.25) | (−1.39) | (1.24) | (−1.37) | |
| lnRev | 0.900*** | 0.985*** | 0.900*** | 0.986*** | 
| (51.43) | (28.33) | (51.54) | (28.34) | |
| D | −0.014 | −0.012 | −0.014 | −0.011 | 
| (−1.35) | (−0.69) | (−1.35) | (−0.58) | |
| lnRev * D | −0.137*** | −0.293*** | −0.137*** | −0.284*** | 
| (−3.37) | (−3.68) | (−3.37) | (−3.59) | |
| SP * lnRev * D | 0.007 | 0.027** | 
 | 
 | 
| (0.46) | (2.41) | 
 | 
 | |
| SP * lnRev | −0.013** | −0.001 | 
 | 
 | 
| (−2.40) | (−0.27) | 
 | 
 | |
| SP * D | −0.003 | 0.004** | 
 | 
 | 
| (−0.51) | (2.38) | 
 | 
 | |
| SPSC * lnRev * D 
 | 
 | 
 | 0.000 | 0.001** | 
| 
 | 
 | (0.78) | (2.23) | |
| SPSC * D | 
 | 
 | −0.000*** | −0.000 | 
| 
 | 
 | (−3.23) | (−0.17) | |
| Control variables | control | control | control | control | 
| Year | control | control | control | control | 
| Obs | 2772 | 856 | 2772 | 856 | 
| R-squared | 0.888 | 0.926 | 0.888 | 0.926 |