Where: = log of oil price (US$ per barrel);
The bounds testing procedure is based on the joint F-statistic (or Wald statistic) for cointegration analysis. The
asymptotic distribution of the F- statistic is non-standard under the null hypothesis of no cointegration between
examined variables. Pesaran and Pesaran (1997) and Pesaran et al. (2001) report two sets of critical values for a
given significance level. One set of critical values assumes that all variables included in the ARDL model are I(0),
while the other is calculated on the assumption that the variables are I(1). If the computed test statistic exceeds the
upper critical bounds value, then the Ho hypothesis is rejected. If the F-statistic falls into the bounds then the
cointegration test becomes inconclusive. If the F-statistic is lower than the lower bounds value, then the null
hypothesis of no cointegration cannot be rejected (Odhiambo, 2010).