Eciency measurement in Two-Stage network structures consideringundesirable outputs

Since data envelopment analysis (dea) introduced in 1970s, it has been widely applied to measure theeciency of a wide variety of production and operation systems. recently dea has been extendedto examine the eciency of decision making units (dmus) with two-stage network structures orprocesses, where the outputs from the rst stage are intermediate measures that make up the inputs ofthe second stage. many researchers developed several dea based models for evaluating the ecienciesof such systems. this paper considers evaluation of the general two-stage network structures, whileeach stage may produce undesirable output, in addition to desirable ones. the developed model isapplied to green hen poultry chain in guilan province, iran.