Current work on price dispersion largely falls into four streams: (1) comparisons between online and offline price dispersion, (2) persistence of online price dispersion, (3) sources of online price dispersion, and (4) consequences of price dispersion. The first three types were derived from Pan's (2004) review, and they are in line with the summaries presented in many studies (Ghose and Yao, 2011 and Maxwell et al., 2011)