In this paper, we consider a wide class of time-varying multivariate causal processes which nests many classic and new examples as special cases. We first prove the existence of a weakly dependent stationary approximation for our model which is the foundation to initiate the theoretical...

This study reviews the empirical literature on the integration properties of energy consumption and production. The survey begins with a discussion of the implications of whether energy variables contain a unit root and proceeds to examine how results differ according to the specific unit root...