Level

First Difference

ADF

PP

ADF

PP

Variables

Constant

Constant & trend

Constant

Constant & trend

Constant

Constant & trend

Constant

Constant & trend

I (d)

$\ln GDP{C}_t$

−0.44

(0.889)

−1.54

(0.793)

−0.08

(0.943)

−2.76

(0.218)

−5.20***

(0.000)

−4.92***

(0.001)

−5.17*** (0.000)

−4.92***

(0.001)

I (1)

$\ln CO{P}_t$

−1.00

(0.741)

−2.36

(0.391)

−1.00

(0.741)

−2.36

(0.391)

−5.58***

(0.000)

−5.54***

(0.000)

−5.57***

(0.000)

−5.53***

(0.000)

I (1)

$\ln EX{C}_t$

−2.93*

(0.051)

-1.81

(0.675)

-2.91*

(0.053)

−1.23

(0.887)

−3.50**

(0.013)

−4.31***

(0.008)

−3.53**

(0.012)

−4.30***

(0.008)

I (0)