RETRACTED: Investigating the efficiency in oil futures market based on GMDH approach

This article has been retracted at the request of the Editor-in-Chief. Please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).Reason: This article has copied material previously published in the article “Are there exploitable inefficiencies in the futures market for oil?”, Shambora et. al., Energ. Econ., 29 (2007) 18–27, doi:10.1016/j.eneco.2005.09.004.As such, this article represents a severe abuse of the scientific publishing system and a clear violation of publishing ethics, and therefore must be retracted.