to the confirmatory data analysis, the ADF and KPSS tests are performed jointly.
Both tests are conducted with intercept and time trend. The number of lagged first
differences in the ADF test is selected based on Schwarz Information Criterion
(SIC). The choice of bandwidth parameter in the Bartlett kernel based sum-ofcovariances
estimator in the KPSS test is selected based on NeweyWest data-based
automatic bandwidth parameter methods. The results of unit root tests are reported
in Table 3. Both ADF and KPSS tests suggest that GDPP and DI are I(1). The results
of unit tests for OFDI are contradictory. ADF test suggests that OFDI is I(1), but
KPSS test suggests that it is I(0). Both ADF and KPSS tests suggest that OPEN is
non-stationary. But, ADF test indicates that OPEN is I(1) and KPSS test suggests
that OPEN is I(2).