variable | Measurement method |

R & D investment | ln (Research and development costs + 1) |

Interest expense ratio | ln (Interest expense/Total fixed assets) |

Current assets ratio | ln (Total current assets/Total assets) |

Per capita output | ln (Industrial production value of the year/Total employee at the end of the year) |

Debt ratio | ln (Total Liabilities/Total assets) |

Long-term debt ratio | ln (Total long-term liabilities/Total assets + 1) |

Business age | Present year- Year of establishment |

Capital intensity | ln (Total fixed assets/Total employee at the end of the year) |