| Level | 1st Difference | ||||

Variable | lag included | ADF test statistics | p−value | lag included | ADF test statistics | p−value |

y | 7 | −1.173 | 0.991 | 6 | −6.726 | 0.000 |

d | s4 | −1.813 | 0.692 | 3 | −4.650 | 0.000 |

nd | 5 | −2.413 | 0.371 | 4 | −3.618 | 0.007 |

f | 4 | −1.815 | 0.692 | 3 | −7.724 | 0.000 |

s | 4 | −1.565 | 0.801 | 3 | −4.475 | 0.000 |

o | 4 | −0.225 | 0.992 | 3 | −4.575 | 0.000 |