an efficiency measurement model in fuzzy environments, using data envelopment analysis

data envelopment analysis (dea) is a technique used to compare efficiency in various sectors such as hospitals, chain stores, and dealerships. it represents a set of linear programming techniques and uses deter-ministic data (inputs and outputs), in stable conditions. the dea technique cannot be used when there is data with indeterministic nature, or when there is an environment with dynamic conditions. to address this prob-lem, dea models can be developed based on linear programming in fuzzy environments (fuzzy dea).most fuzzy dea models introduced in the literature are parametric models based on alpha cuts. however, the model introduced in this study is non-parametric and uses fuzzy l-r numbers. from the theory point of view, the objective of this study is to develop a simple and effective fuzzy dea model. from the practicality point of view, this model can be applied to assess many issues associated with qualitative factors.