“…Though there have been a number of studies investigating the presence of a unit root in energy consumption (Chen and Lee, 2007;Narayan and Smyth, 2007;Hsu et al, 2008;Mishra et al, 2009;Lean and Smyth, 2009;Rao and Rao, 2009), only a few studies examine oil production. 4 In the process of examining the economic, geological, and institutional determinants of oil production in the lower 48 U.S. states, Kaufmann and Cleveland (2001) use the Augmented Dickey Fuller (ADF, Dickey and Fuller, 1979) unit root test with respect to oil production over the period 1938 to 1991.…”