Testing for differences in technical efficiency among groups within an industry

This study generalizes the test performed by Simar and Zelenyuk (2007) to examine differences in the technical efficiency among (Formula presented.) groups within an industry (where (Formula presented.)). For this purpose, the (Formula presented.) groups are divided into pairs and each group is compared with all other (Formula presented.) groups. The (Formula presented.) groups can then be classified into three cohorts: those performing better, equally and worse, relative to the benchmark group. For illustration purposes, annual data for Vietnamese banks covering the period 2005‒2012 is used.