Few studies have however examined the credibility of expert recommender systems (Yoo and Gretzel 2006, 2008, 2011), ambivalent online reviews (Xie et al. 2011), and the impact of online travel reviews on credibility of hotels (Sparks and Browning 2011). Thus, despite the rising interest in social media, our understanding of the role of credibility in the usage process is limited.