| Variable type | Variable symbol | Variable name | Variable definition |
| Dependent variable | RD | R&D expenditure | Various expenses in the process of research and development. |
| Patents | patents | Protected exclusive interests owned by an R&D originator. | |
| Invention | invention | New solutions in products, designs and methods. | |
| Utilitymodel | utility model | Different schemes for shape or internal structure. | |
| Design | appearance design | Put forward new schemes for appearance, shape, color, pattern, etc. | |
| Independent variable | Relationship | social relationship between CEO and independent director | When they have one of the following social relationship: colleagues, alumni, fellow townsmen (born in the same prefecture level city) or joining the same social group, the value is “1”, otherwise it is “0”. |
| control variable | Size | company size | Natural logarithm of total assets of the company. |
| Roa | return on assets | Net profit/total assets. | |
| Mb | market-to-book ratio | Market value/book value. | |
| Lev | debt operation ratio | Total liabilities/total assets. | |
| Cash | operating cash flow | Operating cash flow/total assets. | |
| Year | year dummy | Year dummy variable from 2007 to 2019. | |
| Industry | industry dummy | Defined according to the industry classification of CSRC. | |
| Intermediary variable | Soe | property rights | “state-owned” value is “1”, otherwise the value is “0”. |
| Dummyinsti | proportion of institutional shareholders | When it is higher than the median value of the sample, take “1”, otherwise take “0”. | |
| Dual | separation or combination of chairman and CEO positions | “1” is taken for separation, otherwise “0” is taken. | |
| Dummydir | proportion of independent directors in the board of directors | If it is higher than the median (1/3) of the sample, the value is “1”, otherwise it is “0”. | |
| Dummysize | company size | When the total assets of the company are greater than the median of all sample data, the value is “1”, otherwise it is “0”. | |
| Dummyage | company age | When it is greater than the median of all sample data, the value is “1”, otherwise it is “0”. | |
| Dummydiv | dividend policy | The value of “cash dividend” is “1”, otherwise it is “0”. | |
| DummyKZ | KZ index | When the KZ index is greater than the mean value of all sample data, the value is “1”, otherwise it is “0”. |