Extensions and new developments in DEA

The extensions, new developments and new interpretations for DEA covered in this paper include: (1) new measures of efficiency, (2) new models and (3) new ways of implementing established models with new results and interpretations presented that include treatments of ‘congestion’, ‘returns-to-scale’ and ‘mix’ and ‘technical’ inefficiencies and measures of efficiency that can be used to reflect all pertinent properties. Previously used models, such as those used to identify ‘allocative inefficiencies’, are extended by means of ‘assurance region’ approaches which are less demanding in their information requirements and underlying assumptions. New opportuntiies for research are identified in each section of this chapter. Sources of further developments and possible sources for further help are also suggested with references supplied to other papers that appear in this volume and which are summarily described in this introductory chapter.