other Mathematical Modeling and Applications of OR Mathematical Modeling and Applications of OR پژوهشی Original <span style="font-size:11pt"><span style="line-height:normal"><span style="text-autospace:none"><span style="font-family:&quot;Times New Roman&quot;,serif"><i><span style="color:black"><span style="letter-spacing:-.25pt">Data Envelopment Analysis is one of the most appropriate methods in Evaluation of decision-making units in the real world. That is why researchers have always tried to improve and develop existing methods and approaches in this field. Network Data Envelopment Analysis is used to evaluate the efficiency of network systems by considering processes within divisions. In the evaluation of network systems, one of the challenges is the presence of undesirable and non-discretionary data in the system. Not many conducted have been done about the simultaneous presence of these factors in general two-stage network systems. For this reason, by extending CCR model and combining some methods in this study, we presented a model that is able to evaluate two-stage systems with the mentioned conditions. One of the strengths of the proposed model in this study is the achievement of the efficiency of the system and divisions simultaneously. At the end of the article, we analyzed the results with a numerical example. The results show the ability of the presented model in evaluating the systems under investigation.</span></span></i><i><span style="color:black"><span style="letter-spacing:-.25pt"></span></span></i></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:normal"><span style="text-autospace:none"><span style="font-family:&quot;Times New Roman&quot;,serif"><i><span style="font-size:10.0pt"><span style="color:black"><span style="letter-spacing:-.25pt"></span></span></span></i></span></span></span></span><br> &nbsp; Network data envelopment analysis, ‎Evaluation, Efficiency, Non-discretionary data, Undesirable data. 83 95 http://iors.ir/journal/browse.php?a_code=A-10-1422-70&slc_lang=other&sid=1 Jafar Pourmahmoud Jafar Pourmahmoud pourmahmoud@azaruniv.ac.ir 1111111111 1111111111 Yes Department of Applied Mathematics of Azarbaijan Shahid Madani University, Tabriz, Iran Department of Applied Mathematics of Azarbaijan Shahid Madani University, Tabriz, Iran Davood Norouzi Bene Davood Norouzi Bene noroozee.d@gmail.com 1111111111 1111111111 No Department t of Applied Mathematics of Azarbaijan Shahid Madani University, Tabriz, Iran Department t of Applied Mathematics of Azarbaijan Shahid Madani University, Tabriz, Iran