Variable Type | Variable Measure | Variable Sign | Variable Interpretation |

Dependent variable | Audit fees | LAF | Natural logarithm of audit fee |

Independent variable | City-level | City L | City L = 1 if audit firm and company in a same city |

Economic scale | Scale | Total income Percentile Ranking based on regional -level | |

Cross terms | City L × Scale |
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Control variable | Company size | Size | Natural logarithm of total asset |

Short-term Liquidity | Cata | Current assets/current liabilities | |

Liquidity solvency | Quick | Quick assets/current liabilities | |

Operational capability | LEV | Total liabilities/total assets | |

Profitability capability | ROI | Pre-tax income/total assets | |

Growth capacity | Growth | Growth rate of operating income | |

Lasting capacity | Loss | Loss = 1 if Net profit less than0,or loss = 0 | |

Audit opinion | Op | Op = 1 if give Standard without reservation, or op = 0 | |

Regression year | Year | Fixed variable | |

Regression industry | Industry | Fixed variable |