Gary Simpson
Aston University
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Publication
Featured researches published by Gary Simpson.
Journal of the Operational Research Society | 2004
M.C.A. Silva Portela; Emmanuel Thanassoulis; Gary Simpson
This paper is drawn from the use of data envelopment analysis (DEA) in helping a Portuguese bank to manage the performance of its branches. The bank wanted to set targets for the branches on such variables as growth in number of clients, growth in funds deposited and so on. Such variables can take positive and negative values but apart from some exceptions, traditional DEA models have hitherto been restricted to non-negative data. We report on the development of a model to handle unrestricted data in a DEA framework and illustrate the use of this model on data from the bank concerned.
Journal of the Operational Research Society | 2010
K De Witte; Emmanuel Thanassoulis; Gary Simpson; Giuliana Battisti; A. Charlesworth-May
AbstractThis paper discusses the use of the non-parametric free disposal hull (FDH) and the parametric multi-level model (MLM) as alternative methods for measuring pupil and school attainment where hierarchical structured data are available. Using robust FDH estimates, we show how to decompose the overall inefficiency of a unit (a pupil) into a unit specific and a higher level (a school) component. By a sample of entry and exit attainments of 3017 girls in British ordinary single sex schools, we test the robustness of the non-parametric and parametric estimates. Finally, the paper uses the traditional MLM model in a best practice framework so that pupil and school efficiencies can be computed.
European Journal of Operational Research | 2010
Tarik Driouchi; David Bennett; Gary Simpson
This note presents a contingent-claims approach to strategic capacity planning. We develop models for capacity choice and expansion decisions in a single firm environment where investment is irreversible and demand is uncertain. These models illustrate specifically the relevance of path-dependent options analysis to planning capacity investments when the firm adopts demand tracking or average capacity strategies. It is argued that Asian/average type real options can explain hysteresis phenomena in addition to providing superior control of assets in place.
Journal of the Operational Research Society | 2005
Gary Simpson
Data envelopment analysis (DEA) is a popular non-parametric technique for determining the efficiency of a homogeneous set of decision-making units (DMUs). In many practical cases, there is some doubt if the all the DMUs form a single group with a common efficiency distribution. The Mann–Whitney rank statistic has been used in DEA both to test if two groups of DMUs come from a common efficiency distribution and also to test if the two groups have a common frontier, each of which are likely to have important but different policy implications for the management of the groups. In this paper it is demonstrated that where the Mann–Whitney rank statistic is used for the second of these it is likely to overestimate programmatic inefficiency, particularly of the smaller group. A new non-parametric statistic is proposed for the case of comparing the efficient frontiers of two groups, which overcomes the problems we identify in the use of the Mann–Whitney rank statistic for this purpose.
OR Insight | 1999
Gary Simpson
Thanassoulis and Simpson (1999) outlined an approach for setting targets by DEA for individuals that will be realistic yet demanding. The approach featured the use of DEA to identify ‘exceptional’ individuals who should be dropped as potential referents so that the targets would be more realistic. The paper used the example of setting achievement targets for school children. Tie technical details to identifying exceptional individuals were contained in an Appendix that was inadvertently omitted from Thanassoulis and Simpson (1999). This note presents the Appendix both in the context of setting targets and more generally as a method for identifying outliers.
Archive | 2008
Chuc Dinh Nguyen; Gary Simpson; David S. Saal; Anh Ngoc Nguyen; Ngoc Quang Pham
Journal of the Operational Research Society | 2000
Gary Simpson; John S. Edwards
Journal of Productivity Analysis | 2007
Gary Simpson
OR Insight | 1999
Emmanuel Thanassoulis; Gary Simpson
Archive | 2009
Gary Simpson