| variables | Sample size | Mean value | standard deviation | minimum value | maximum value | unit |
| LnCI | 600 | 8.61 | 0.94 | 4.68 | 10.36 | ten thousand tons |
| LnPGDP | 600 | 10.00 | 0.84 | 7.92 | 12.01 | yuan |
| IS | 600 | 1.22 | 0.74 | 0.35 | 5.32 | % |
| FDI | 600 | 0.03 | 0.02 | 0.00 | 0.15 | % |
| URB | 600 | 0.52 | 0.15 | 0.23 | 0.90 | % |
| R&D | 600 | 0.01 | 0.01 | 0.00 | 0.07 | % |
| ELE | 600 | 0.13 | 0.09 | 0.03 | 0.55 | KWH/yuan |
| LnPOP | 600 | 5.43 | 1.27 | 1.97 | 8.28 | Persons/square km. |