| Control variable | Variable symbol | Variable definition and calculation |
| Company size | Size | Ln(Total assets at the end of the year) |
| Enterprise profitability | ROA | Net profit/total assets |
| Financial risk | LEV | Total liabilities/total assets |
| Cash flow | CFO | Net operating cash flow/total assets at the end of the period |
| Realization rate of tangible assets | Inver | Net inventory and accounts receivable divided by total liabilities |
| Nature of enterprise property rights | Soe | If the largest shareholder of the enterprise is state-owned, it is assigned as 1, otherwise it is 0 |