Variables | Code | Definitions |

R & D intensity | RD | R & D expenses/corporate main business income |

Overconfidence | OC | If the number of shares held by the executive team in this year is more than that in the previous year, OC equals 1; otherwise OC equals 0 |

Financing constraints | FC | If the SA index of a observation is less than the mean of all observations, FC equals 1. Otherwise FC equals 0. |

Firm size | SIZE | Natural logarithm of total assets |

Asset-liability ratio | LEV | Total assets/Total liabilities |

Tobin q | TBQ | Market value of assets/The book value of assets |

Return on assets | ROA | Net profit/Average total assets |

Ownership concentration | SHARE | The proportion of the first largest shareholder |

Duality | DUA | If the chairman and general manager are the same person, DUA equals 1; otherwise DUA equals 0 |