Improving envelopment in Data Envelopment Analysis under variable returns to scale

Emmanuel Thanassoulis*, Mika Kortelainen, Rachel Allen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


In a Data Envelopment Analysis model, some of the weights used to compute the efficiency of a unit can have zero or negligible value despite of the importance of the corresponding input or output. This paper offers an approach to preventing inputs and outputs from being ignored in the DEA assessment under the multiple input and output VRS environment, building on an approach introduced in Allen and Thanassoulis (2004) for single input multiple output CRS cases. The proposed method is based on the idea of introducing unobserved DMUs created by adjusting input and output levels of certain observed relatively efficient DMUs, in a manner which reflects a combination of technical information and the decision maker's value judgements. In contrast to many alternative techniques used to constrain weights and/or improve envelopment in DEA, this approach allows one to impose local information on production trade-offs, which are in line with the general VRS technology. The suggested procedure is illustrated using real data. © 2011 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)175-185
Number of pages11
JournalEuropean Journal of Operational Research
Issue number1
Publication statusPublished - 1 Apr 2012


  • data envelopment analysis
  • efficiency
  • productivity
  • unobserved DMUs
  • value judgements


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