“…Ratio analysis, a conventional measurement method for efficiency, requires the weight on various inputs and outputs to be predetermined, thereby leading to the subjective judgment of researchers (Berger & Humphrey, 1997). Based on these advantages, DEA is considered superior to other methods for a minimal required assumption and has been widely used for efficiency measurement in the service sector (Liu et al, 2018), including in retail (Keh & Chu, 2003), Internet marketing (Shuai & Wu, 2011), mobile phone brands (Bayraktar et al, 2012), and banking (Ebrahimnejad et al, 2014;Soteriou & Stavrinides, 2000).…”