Variable

Hadri test

LLC test

Null: No unit root

Null: Unit root

X_ij

14.7744 (0.0000)^***

0.49518 (0.6898)

GDP_i

17.1184 (0.0000)^***

−4.59292 (0.0000)^***

GDP_j

17.0063 (0.0000)^***

1.24253 (0.8930)

POP_j

17.9277 (0.0000)^***

−47.63495 (0.0000)^***

OPN_j

11.4271 (0.0000)^***

−43.54018 (0.0002)^***