I use the bounds testing approach to co-integration developed by Pesaran et al.
(2001) to test for the existence of a long-run relationship. This test is based on
autoregressive distributed lag (ARDL) framework. It is utilized here because Pesaran
and Shin (1999) show that the OLS estimators of ARDL parameters are nconsistent,
where n is sample size and the estimators of the long-run coefficients are
super-consistent in small sample sizes. Furthermore, this approach can be used
irrespective of whether the variables are pure I(1), I(0) or mutually co-integrated.
Many unit root tests are available. In this study, I use only two of them, augmented
Dickey and Fuller (1979, 1981) test (ADF test) and the test proposed by Kwiatkowski
et al. (1992) (KPSS test). The null hypothesis of the ADF test as a series is nonstationary,
whereas the null hypothesis of the KPSS test as a series is stationary. Due