(4)

(5)

(6)

lnRGDP

0.38***

(0.11)

2.29***

(0.54)

−16.87***

(4.18)

lnRGDP²

−0.09***

(0.03)

1.86***

(0.42)

lnRGDP³

−0.06***

(0.01)

IS

−0.17***

(0.04)

−0.15***

(0.04)

−0.13***

(0.04)

FDI

−1.31**

(0.66)

−2.17***

(0.68)

−1.84***

(0.68)

URB

2.48***

(0.47)

2.53***

(0.47)

1.88***

(1.88)

R&D

−5.49*

(3.18)

−5.77*

(3.41)

−10.24***

(3.54)

ELE

2.38***

(0.37)

2.87***

(0.39)

2.60***

(0.40)

lnPOP

0.66***

(0.22)

1.27***

(0.27)

1.46***

(0.27)

A-R²

0.7767

0.7841

0.7551

Log-likelihood

192.36

201.18

215.86

rho

0.24***

0.27***

0.34***