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چکیده
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Estimating of returns to scale in data envelopment analysis is discussed in this paper. Banker [1] introduced concept of most productive scale size (mpss) in DEA. One of approaches for determining mpss is α-β model proposed in Cooper, Thompson and Thrall [2]. The direct solving of that model is rather difficult because the objective function is fractional. Hence Jahanshahloo and Khodabakhshi [3] introduced a model with output–input orientation which objective function is linear. Here, we will show their linear programming model can be used to determine return to scale of decision making units (DMU). The applicability of the model developed is illustrated in the context of the analysis of railway companies' performance. The results obtained in the case study showed that the DEA models can provide robust estimates RTS. In this paper we used of six input and output variables so that, rail lines, labour, number of wagon and total revenue as input variables and passenger-km and Ton-km as output variables.
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