Variables | ADF test (statistics) | PP test (statistics) | Tr./Fd. | Unit root | ADF-GLS |
---|

*τ*-statistics | ADF-GLS critical value (5%) |
---|

EG_{R} | 2.734 | *P* = 0.433 | 5.673 | *P* = 0.761 | None | Yes | − 2.713 | − 2.996 |

EU_{A} | − 1.122 | *P* = 0.391 | 0.015 | *P* = 0.153 | Tr. + Fd. | Yes | − 2.510 | − 2.744 |

EP | − 3.249 | *P* = 0.127 | 3.805 | *P* = 0.368 | Fd. | Yes | − 2.119 | − 2.913 |

HC_{IN} | 5.347 | *P* = 0.849 | 2.654 | *P* = 0.294 | Fd. | Yes | − 2.885 | − 3.185 |

ΔEG_{R} | − 2.950 | *P* = 0.035 | − 3.930 | *P* = 0.050 | None | No | − 2.947 | − 2.270 |

ΔEU_{A} | − 2.509 | *P* = 0.005 | − 4.667 | *P* = 0.003 | Tr. + Fd. | No | − 3.125 | − 3.002 |

ΔEP | − 6.623 | *P* = 0.018 | − 6.043 | *P* = 0.005 | Fd | No | − 2.983 | − 2.316 |

ΔHC_{IN} | − 5.665 | *P* = 0.036 | − 3.823 | *P* = 0.020 | Tr. + Fd. | No | − 2.722 | − 2.601 |

- If
*p* value > 0.05, then do not reject the null hypothesis of unit root *EG*_{R} renewable energy generation, *EU*_{A} aggregated energy use, *EP* economic performance, *HC*_{IN} human capital index, *ADF* augmented Dickey-Fuller test, *PP* Phillips-Perron test, *GLS* generalized least square, Δ a first-order difference of variables, *Tr.* trend, *Fd.* fixed, *τ* ADF-GLS test values, *P* probability value