| Types | Variables | Abbreviation | Index |
| Explained variable | Capital structure | LEV | Asset-liability ratio |
| Explanatory variables | Size | SIZE | Natural logarithm of total assets |
| Growth | GROWTH | (Final total assets-initial total assets)/Initial total assets | |
| Tangible assets ratio | TA | (Inventory + fixed assets)/Total assets | |
| Unique of the products | UP | Sales expenses/Sales revenue | |
| Shareholding concentration | SC | Stock proportion of the first shareholder | |
| Non-debt tax shield | NTS | Depreciation/Total assets | |
| Asset liquidity | AS | Current assets/Current liabilities | |
| Profitability | PRO | Profit ratio of sales |