“…We consider the West Texas Intermediate crude oil prices (WTI) as a proxy for crude oil. Recently, Alquist and Kilian (2010) [15], Alquist et al (2013) [18], Baumeister et al (2013Baumeister et al ( , 2014Baumeister et al ( , 2015 [13,17,19], [12], Xiong et al (2013) [20], Yin and Yang (2016) [21], Drachal (2016) [10] and Naser (2016) [11] all regarded WTI as a proxy variable for oil prices. We selected four factors: supply, demand, crack spread, and non-energy commodity prices.…”