Table 1.

Stationarity test results.

Groups	Series	At level		At 1st difference		At 2nd difference		Order of integration
		t-Statistic	Prob.	t-Statistic	Prob.	t-Statistic	Prob.
World	lnCE	1.0536	0.9958	−3.2862	0.0276	–	–	I(1)
	lnperCE	0.5703	0.9856	−3.1509	0.0366	–	–	I(1)
	lnTRD	−1.2539	0.6334	−6.1589	0.0000	–	–	I(1)
	lnFDI	−1.4974	0.5177	−3.7939	0.0091	–	–	I(1)
	lnEC	0.8330	0.9925	−4.0289	0.0054	–	–	I(1)
	lnEI	−0.0967	0.9372	−3.5141	0.0185	–	–	I(1)
	lnES	−0.9469	0.7549	−3.6449	0.0127	–	–	I(1)
HI	lnCE	−2.3230	0.1732	−4.9820	0.0006	–	–	I(1)
	lnperCE	−0.5883	0.8557	−4.9721	0.0006	–	–	I(1)
	lnTRD	−0.6986	0.8288	−5.7642	0.0001	–	–	I(1)
	lnFDI	−1.4170	0.5570	−3.8226	0.0086	–	–	I(1)
	lnEC	−1.7820	0.3798	−4.9654	0.0006	–	–	I(1)
	lnEI	1.3796	0.9983	−4.5404	0.0017	–	–	I(1)
	lnES	−0.7538	0.8141	−4.3947	0.0025	–	–	I(1)
MIa	lnCE	0.0079	0.9501	−2.1688	0.2220	−5.1066	0.0006	I(2)
	lnperCE	−0.3087	0.9093	−2.0967	0.2476	−5.0830	0.0006	I(2)
	lnTRD	−2.3574	0.1636	−5.1978	0.0004	–	–	I(1)
	lnFDI	−4.6042	0.0013	–	–	–	–	I(0)
	lnEC	−0.2000	0.9255	−2.1156	0.2407	−6.3001	0.0000	I(2)
	lnEI	−0.3271	0.9068	−2.9136	0.0598	−6.0552	0.0001	I(2)
	lnES	−0.8779	0.7767	−2.3269	0.1725	−6.6335	0.0000	I(2)

^aMI (which is also written as MIG) refers to middle-income level group, which consists of upper-middle income level group and lower-middle income level group.