Imperfect and defective outputs in production process

Data envelopment analysis (dea) has been proven as an excellent data-oriented eciency analysis methodwhen multiple inputs and outputs are present in a set of decision making units (dmus). in conventional deawe assume that the produced outputs are perfect. however in real applications, there are systems which theirproduced outputs are possibly imperfect and defective. these outputs enter the system as inputs once againand after rebuilding, they will be completed. the present paper proposes a modication of the standard deamodel to incorporate such imperfect outputs. numerical example is used to demonstrate the approach.