TY - JOUR T1 - Cost Efficiency Evaluation via Data Envelopment Analysis Approach for Undesirable Outputs based on the Weak Disposability Axiom (Case Study: 56 Electricity Producing Thermal Power Plants in Iran) TT - ارزیابی کارایی هزینه با رویکرد تحلیل پوششی داده‌‌ها با در نظر‌گرفتن خروجی‌های نامطلوب مبتنی بر اصل دسترسی‌پذیری ضعیف (مطالعه موردی: ‌۵6 نیروگاه حرارتی ‌تولید برق ‌کشور) JF - JAMLU JO - JAMLU VL - 16 IS - 4 UR - http://jamlu.liau.ac.ir/article-1-1843-en.html Y1 - 2019 SP - 109 EP - 131 KW - Cost efficiency‎ KW - Undesirable Outputs KW - Weak Disposability Axiom KW - Data Envelopment Analysis N2 - Cost efficiency evaluation is a very important and applicable issue in Data Envelopment ‎Analysis (DEA). In this paper, the classical cost efficiency model in which all the input ‎prices are known and fixed for each decision making unit is developed via undesirable ‎outputs with the weak disposability axiom. The proposed model is a nonlinear model ‎under the variable returns to scale condition, which is linearized for the purposes of easy ‎solving. In order to simulate the proposed model and demonstrate its advantages and ‎application capabilities, 56 electricity producing thermal power plants were studied based ‎on data set that is presented in 2015. According to the simulation results based on the ‎present method, the combined cycle and steam power plants had the highest cost ‎efficiencies under the both assumed conditions, i.e., the constant returns to scale and the ‎variable returns to scale. Moreover, the average cost efficiencies of the power plants were ‎‎36% and 54% under the assumed conditions of constant returns to scale and variable ‎returns to scale, respectively.‎ M3 ER -