Groups Performance Ranking Based on Inefficiency Sharing

In the real world there are groups which composed of independent units. the conventional dataenvelopment analysis(dea) model treats groups as units, ignoring the operation of individual unitswithin each group.the current paper, investigates parallel system network approach proposed by kaoand modies it. as modied kao' model is more eligible to recognize ecient groups, a new rankingmethod is proposed based on a model which calculates eciencies with additional constraint thatmade model share constant ineciency among groups.to show advantages, modies model is appliedto eciency calculation of both articial and real groups and results is compared with conventionaldea model and parallel system network model as well.finally it is shown by tow numerical andempirical examples that ecient groups recognized by modied model how can be ranked accordingto proposed ranking model.