document: Modeling undesirable factors in efficiency evaluation Data envelopment analysis -LRB- DEA -RRB- measures the relative efficiency of decision making units -LRB- DMUs -RRB- with multiple performance factors which are grouped into outputs and inputs . Once the efficient frontier is determined , inefficient DMUs can improve their performance to reach the efficient frontier by either increasing their current output levels or decreasing their current input levels . However , both desirable -LRB- good -RRB- and undesirable -LRB- bad -RRB- factors may be present . For example , if inefficiency exists in production processes where final products are manufactured with a production of wastes and pollutants , the outputs of wastes and pollutants are undesirable and should be reduced to improve the performance . Using the classification invariance property , we show that the standard DEA model can be used to improve the performance via increasing the desirable outputs and decreasing the undesirable outputs . The method can also be applied to situations when some inputs need to be increased to improve the performance . The linearity and convexity of DEA are preserved through our proposal
doc_bio_tags: O O O O B I B I I O O O O O O O O B I I O O O O B I I O O O O O O O O O O B I O O O O O O O O O O O O B I O O O O B I I O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O B O B O O O O B O B O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O B I O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O