Narayan, Paresh Kumar; Liu, Ruipeng - In: Applied Energy 88 (2011) 1, pp. 409-416
This paper considers the issue of whether shocks to ten commodity prices (gold, silver, platinum, copper, aluminum, iron ore, lead, nickel, tin, and zinc) are persistent or transitory. We use two recently developed unit root tests, namely the Narayan and Popp (NP) [14] test and the Liu and...