Abstract:

Data Envelopment Analysis (DEA) is a tool to assess relative efficiencies with a group of decision making units (DMUs). As in ranking process, it  the best and worst efficiency scores of a DMU are compared at the same time, the results will be more reasonable. The CEF (complete envelopment frontier) based on super efficiency DEA model, virtual DMU and nonradial C2GS2 model were used in DMUs with independent subsystems, then a new twostages model which considering the preference of decisionmaker or the importance of different index were proposed. Final, the data example proves that the ranking results of the improved model are fair, reasonable and full.

Key words: complete enveloping surface; virtual DMU; non-radial C2GS2model; two-stage