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European
Journal of Operational Research Book Review
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Carlos
Henggeler Antunes
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EJOR,
2006 , Vol. Issue ,
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William W. Cooper, Lawrence M.
Seiford and Joe Zhu, International Series in Operations Research and
Management Science, Kluwer Academic Publishers (2004) ISBN
1-4020-7797-1.
This handbook on data
envelopment analysis, edited and
authored by some of the most prominent researchers in the field of DEA,
aims at being a comprehensive reference for researchers, students and
practitioners, and a milestone in the DEA progression. The
handbook is
organized into three main parts. The first one covers the basic DEA
models as well as some extensions, including sensitivity analysis, the
incorporation of value judgments in DEA models, the use of distance
functions, the consideration of qualitative data, the identification
and management of congestion within DEA models, the efficiency change
over time captured through the Malmquist index, chance constrained
models, the performance of bootstrap techniques, and statistical tests
based on efficiency scores. The second part consists in
application-oriented papers in the areas of education, banking,
engineering, sports, retailing and health care. The last part is a
state-of-the-art survey of DEA software tools.
The
book comprises 18 chapters written by 29 contributors. In chapter 1,
authored by the editors, the background and history of DEA are
revisited and the various models and methods for treating allocative
and overall efficiency are covered. The CCR model is presented in
detail as well as extensions to deal with non-discretionary and
categorical inputs and outputs, incorporation of judgments and a priori
knowledge, and window analysis. A new additive model is also presented
aimed at dealing with allocative and overall efficiency, which can be
used whenever the usual ratio form of the efficiency measure gives
unsatisfactory or misleading results. This model requires unit prices
(associated with output slacks) and unit costs (associated with input
slacks) to assess “profit efficiency”.
The topic addressed in
chapter 2, by Banker, Cooper, Seiford and Zhu, is returns to scale
(RTS) in DEA models. The discussion is centred on the relationships
between DEA models and methods and the qualitative RTS
characterizations they produce (such as whether RTS is identified as
increasing, decreasing or constant). The RTS approaches within BCC and
CCR models are revisited, extending them to models other than radial
measure models.
In chapter 3, by Cooper, Li, Seiford and Zhu,
methods for studying the sensitivity of DEA results to changes in the
data are presented. The focus is the sensitivity of DEA efficiency
evaluation, namely regarding the stability of the classification of the
DMU status into efficient and inefficient. Global data changes are
considered, in the sense that the stability of results is assessed when
inputs and outputs change simultaneously for all DMUs.
The
incorporation of value judgments in DEA models is addressed in chapter
4, by Thanassoulis, Portela and Allen. The important issue of the role
and meaning of weights is revisited, and the main reasons for including
value judgments in DEA models are described (generally motivated by
real-world applications). Methods for incorporating value judgments and
reducing the flexibility of DMUs in choosing their “value system” are
presented, which are categorized in two broad classes: weight
restrictions (absolute restrictions, assurance regions, and
restrictions on virtual inputs and outputs) and changing the data set
(transforming the data and adding new DMUs). The authors also discuss
the changes that the incorporation of value judgments may introduce on
the efficient frontier and its RTS characteristics.
Chapter 5, by
Fare, Grosskopf and Whittaker, deals with distance functions and their
duality relations. DEA estimations of various distance functions are
presented and it is shown that their support functions (profit, revenue
and cost) also may be estimated via DEA.
In chapter 6, Cook
discusses the treatment of qualitative data in DEA models. The radial
projection DEA model in the presence of ordinal data is examined and
then applied to the efficiency evaluation of R&D projects and a
telephone office. It is shown that by introducing the concept of rank
position data within the DEA structure, the resulting model can be
transformed into a VRS type model. The linking of the ordinal DEA model
to multiple criteria decision making with ordinal data and criteria
importance is also mentioned.
Cooper, Deng, Seiford and Zhu, in
chapter 7, present various approaches to identify and manage congestion
(understood as a form of technical inefficiency) with DEA models. It is
illustrated how the DEA models can be used to determine the effects of
congestion, namely the amount of congesting inputs, the output
reduction due to congestion and the points where technical inefficiency
gives way to congestion.
Chapter 8, by Tone, is a comprehensive
study of the Malmquist productivity index to evaluate the productivity
change of a DMU between time periods. This index includes a catch-up
(recovery) term and a frontier-shift (innovation) term to capture the
effects of both efficiency and technology changes. Three different
approaches for the measurement of the Malmquist index are presented:
radial, non-radial and non-radial and non-oriented. It is shown that
the oriented radial models suffer from the neglect of slacks and
infeasibility.
Chapters 9, 10 and 11 are devoted to probabilistic
and statistical characterizations of the main efficiency evaluation
models. In chapter 9, Cooper, Huang and Li deal with chance constrained
programming extensions of the deterministic DEA formulations, thus
making it possible to use characterizations such as “probably
efficient” and “probably not efficient”. Expected value formulations
are used to discuss DEA efficiency and its relationship with
sensitivity analysis in stochastic situations. Other types of chance
constrained programming models incorporate Simon’s satisficing concepts
to extend the potential uses of DEA to cases in which full efficiency
can be replaced by the attainment of aspiration levels of performance.
Chapter
10, by Simar and Wilson, presents bootstrap methods for statistical
inference within non-parametric efficiency estimation. It is shown, via
Monte Carlo experiments, that the iterated bootstrap offers a
convenient approach for evaluating the performance of the bootstrap and
providing corrections in a given applied context.
Chapter 11, by
Banker and Natarajan, is devoted to statistical tests based on DEA
efficiency scores, showing that the DEA estimator of the production
frontier has desirable statistical properties enabling to develop a
wide range of formal statistical tests. These can be used to test
hypotheses of interest and relevance in the application of DEA such as
existence of scale economies, separability and substitutability of
inputs in production system, comparison of efficiency of groups of
DMUs, etc.
Six DEA application chapters follow. In chapter 12,
Ruggiero deals with DEA applications in education, one of the public
sector activities in which a large amount of funds is invested and has
witnessed a growing trend towards the consideration of accountability
and efficiency issues. A discussion of the treatment of
non-discretionary variables is also provided.
Chapter 13, by
Paradi, Vela and Yang, discusses the DEA application to banking and
provides a comprehensive review of the literature on bank branch
performance DEA models (which describes variables, sample, type of RTS
and model-orientation).
Chapter 14, by Triantis, presents the
issues that researchers face when applying DEA to engineering problems,
and proposes an approach for the design of an integrated DEA based
performance measurement system. Moreover, it summarizes studies that
have focused on engineering applications of DEA, and suggests systems
thinking concepts that are appropriate for future DEA research in
engineering. A bibliography of DEA applications in engineering is also
provided.
Chapter 15, by Anderson, shows how DEA can be used to
assess the player who had the most dominant baseball batting season,
using the concept of super-efficiency. The adjusting capability of DEA
to the changing circumstances of the game was recognized as one of its
main strengths.
Chapter 16, by Athanassopoulos, provides a
discussion on the performance of for-profit retail service industries.
The study focus on the development of a unified methodological
framework for assessing the operating efficiency of real networks (512
retail outlets in banking, sales forces, restaurants and betting
shops). The monitoring of marketing and cost efficiency of service
chains contributes to enhance the accountability of the marketing
function and the decision making ability to improve the performance of
individual branches.
Chapter 17, by Chilingerian and Sherman,
focuses on health care applications of DEA. It offers a brief history
of case studies in health sector (from hospitals to physicians) and
discusses some of the models and motivations behind the applications.
An eight-step procedure for DEA health application is provided with
emphasis on the need for including quality measures of the services
delivered.
Chapter 18, by Barr, presents a critical survey of DEA
software packages, both commercial and non-commercial. Besides
descriptions of eight individual packages, comparisons of their
features and capabilities are provided, as well as links to further
information on each of them.
The
handbook is intended for researchers, students and practitioners. It
aims at reflecting the state-of-the-art as well as representing a
milestone in DEA advancing. I found this handbook a valuable reference
for researchers, graduate students, and consultant analysts. However,
it requires a relatively important degree of familiarity with the main
DEA models and extensions to be used as an introductory door to this
field. For this purpose (for instance, for classroom use in
undergraduate classes) other references by the same authors are more
appropriate (Charnes et al., 1994 and Cooper et al., 2000), mainly
because the topics unfolding in more comprehensive, self-contained and
written in a didactic way.
In
this scope, I found all the chapters on the first part of the book,
covering methodological issues, quite interesting and useful, in
particular those devoted to the incorporation of value judgments and
sensitivity analysis in DEA models. The chapters exploring the links
with statistics, devoted to the performance of bootstrap techniques and
statistical tests based on efficiency scores, also unveil important
research directions. However, these chapters require from the reader a
level of expertise on DEA models (as well as other topics), which
cannot be acquired in the handbook itself. The chapter dealing with the
consideration of qualitative data is the only one where the links
between DEA and multiple criteria decision making are briefly explored.
This is a relevant research and application topic and it would have
been useful to have a whole chapter devoted to it.
The second
part of this handbook, regarding application studies, left me with a
sense of “incompleteness”. Of course, it will be impossible to include
chapters, or even mention, all the areas in which DEA applications have
been reported in the literature. Therefore, I believe a more judicious
selection of material to be included should have been done to reflect
state-of-the-art and relevance in DEA applications. The chapters
included in the handbook are interesting and indeed lessons can be
learned therein that can be replicated in studies in other areas.
However, the handbook would have benefited from the inclusion of
chapters describing studies in other (perhaps more relevant) areas,
such as, for instance, energy, agriculture, environment, or
telecommunications. Also, there is some imbalance in the treatment of
applications in the chapters in the second part of the handbook. Some
chapters enter into the details of model description (input and output
factors, type of RTS, etc.) whereas other chapters merely do a survey
of the literature. It goes without saying that both types can be useful
for researchers and practitioners, but a higher consistency on this
specific issue could have been pursued.
Nevertheless, this
handbook provides an important value-added regarding DEA monographs,
even though I think the editors could have organized it more under the
perspective of a valuable complement to the other two books already
mentioned above. This handbook constitutes, namely regarding some
methodological chapters in the first part, an encouraging research
agenda for further developments and uses of DEA. In this scope it is a
valuable tool for researchers, graduate students and experienced
practitioners. Moreover, up-to-date references are provided in most
chapters that enable the reader to develop further his/her own specific
interests in this continuously advancing area.
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