Returns to scale in different DEA models
Rajiv D. Banker a, William W. Cooper b, Lawrence M. Seiford c, Robert M. Thrall d, Joe Zhu e,* c School of Management, The University of Texas at Dallas, Richardson, TX 75083-0658, USA Graduate School of Business, The University of Texas at Austin, Austin, TX 78712-1174, USA Department of Industrial and Operations Engineering, University of Michigan, Ann Arbor, MI 48109-2117, USA d 12003 Pebble Hill Drive, Houston, TX 77024, USA e Department of Management, Worcester Polytechnic Institute, Worcester, MA 01609, USA b a
Abstract This paper discusses returns to scale (RTS) in data envelopment analysis (DEA) for each of the presently available types of models. The BCC and CCR models are treated in input oriented forms while the multiplicative model is treated in output oriented form. (This distinction is not pertinent for the additive model which simultaneously maximizes outputs and minimizes inputs in the sense of a vector optimization.) Quantitative estimates in the form of scale elasticities are treated in the context of multiplicative models, but the bulk of the discussion is confined to qualitative characterizations such as whether RTS is identified as increasing, decreasing or constant. This is discussed for each type of model and relations between the results for the different models are established. The opening section describes and delimits approaches to be examined. The concluding section outlines further opportunities for research. Ó 2003 Elsevier B.V. All rights reserved.
Keywords: DEA; Efficiency; RTS
1. Introduction It has long been recognized that data envelopment analysis (DEA) by its use of mathematical programming is particularly adept at estimating inefficiencies in multiple input and multiple output production correspondences. Following Charnes, Cooper and Rhodes (CCR, 1978), a number of different DEA models have
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