Table Of ContentA Guide to
Operational
Research
A Guide to
Operational
Research
W.E. DUCKWORTH
Managing Director. Fulmer Research Institute
A.E. GEAR
Associate Professor in Management Studies .. Deputy Dean. Faculty of
Commerce, University of Auckland, New Zealand
A.G. LOCKETT
Senior Lecturer in Management Science .. Dean. Faculty of Business
Administration. Manchester University
LONDON NEW YORK
CHAPMAN AND HALL
First published 1962
by Methuen & Co. Ltd
Third edition 1977
published by Chapman and Hall Ltd,
11 New Fetter Lane, London EC4P 4EE
Published in the USA by Chapman and Hall
733 Third Avenue, New York NYlO017
Reprinted 1978, 1982
© 1977 W. E. Duckworth, A. E. Gear, A. G. Lockett
Softcover reprint of the hardcover 1s t edition 1977
ISBN-13: 978-0-412-13500-2 e-ISBN-13: 978-94-011-6910-3
DOl: 10.1007/978-94-011-6910-3
This paperback edition is
sold subject to the condition that it
shall not, by way of trade or otherwise, be
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without the publisher's prior consent in any form of
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including this condition being imposed
on the subsequent purchaser.
All rights reserved. No part of
this book may be reprinted, or reproduced
or utilized in any form or by any electronic,
mechanical or other means, now known or hereafter
invented, including photocopying and recording,
or in any information storage or retrieval
system, without permission in writing
from the publisher.
Contents
Preface by W.E. Duckworth page vii
What operational research is and does
2 Measuring uncertainty 16
3 Queuing problems 32
4 Business forecasting 40
5 Simulation and Monte Carlo Methods 61
6 Stock and production control models 84
7 Resource allocation 105
8 Planning projects 127
9 Analysing decisions 150
10 Operational gaming 167
11 Other operational research techniques 180
12 Conclusions 193
Name Index 201
General Index 203
Preface
There is nothing more difficult to take in hand. more
perilous to conduct. or more uncertain in its success.
than to take the lead in the introduction of a new order of
things. because the innovator has for enemies all those
who have done well under the old conditions. and lukewarm
defenders in those who may do well under the new.
Machiavelli. The Prince
When this book was first written in 1959 I was myself a practising operational
research worker in charge of a small group at the Glacier Metal Company,
concerned with using Operational Research philosophy and techniques to
help solve some of the managerial problems inside the company.
About that time Operational Research was beginning to attract attention
in industrial circles. Many quite large research groups were being founded.
The advertisement columns of the Sunday press and certain daily newspapers
were full of advertisements for Operational Research practitioners, at then
quite attractive salaries.
This interest by industrialists in Operational Research appeared to be
based upon faith and expectation rather than upon experience. Many of
the classical examples of successful Operational Research being used in the
many text-books beginning to appear were still based upon the war-time
experiences recently amplified in the newly released and long classified book
by Waddington. *
The First International Conference on Operational Research held in 1957
attempted to restore the balance by summarizing industrial experience since
the War. Even in that publication, however, many of the case studies were
still incomplete, the outcomes had not yet been fully evaluated, and the
many different types and levels of experience described in the proceedings
of that conference did not produce a sufficiently coherent impression of
post-war Operational Research practice to satisfy the busy manager, seeking
a ready appreciation for his own purposes, as to whether he should seek the
assistance of Operational Research.
The need for such a ready appreciation was described by the late Oscar
Brandt in an editorial in his magazine Metal Treatment in April 1958, and
it was in response to his appeal that I wrote two articles for Metal Treatment
which appeared in September and October of that year. These subsequently
* References are given in alphabetical order of first author at the end of each chapter.
vii
viii Preface
formed the basis of the first edition of A Guide to Operational Research in
1962. This achieved substantially more success than I had expected, or even
dreamed of, because it did provide a relatively simple coherent account by
one individual of successful Operational Research being practised, albeit at
a rather specialized level and not on too grand a scale, in one company.
Most of the examples were written from first-hand experience, so they
possessed both an immediacy and a clarity of exposition that appeared to
be lacking from many other accounts which were at second, third, and some-
times even fourth hand. There appears little doubt that the formula has been
successful because after thirteen years the book was still being reprinted, it
is still selling in several languages, and it has also reached the reading list
of many universities and schools of management.
To be on this reading list has, in recent years, been causing me great
concern because many of the illustrations of Operational Research
techniques had become out of date. The book also did not describe several
more modern techniques. When the book first appeared it was quite rightly
criticized as providing a rather selective view of Operational Research, and
as the years have gone by this criticism has become more justified.
If the book was serving a valuable purpose, as several other reviews then
and subsequently have indicated, in acquainting busy managers in a readily
assimilable fashion of the virtues of Operational Research, then it did seem
to be a dereliction of duty to let the book die and cease publication, because
there did not appear to be another book available that provided for quite
the same purpose. Equally, it appeared wrong to let it continue to get more
and more out of date.
The present version of the book is an attempt to resolve the dilemma with
the aid of two collaborators, Tony Gear and Geoff Lockett. I did not feel
capable of rewriting the book in quite the same way as sixteen years earlier
because I have long ceased to be as closely connected with Operational
Research practice as I was in the late 1950s. Tony Gear and Geoff Lockett
are, however, such practitioners. They both benefited from reading the book
in the early days. Being university teachers as well, they have a personal
and a professional interest in seeing it adequately up-to-date.
We have tried in this up-dating to preserve the coherency of style that
has been such a feature of the earlier book's success. However, the need for
a more detailed exposition of Operational Research Techniques for the
purposes of student teaching has necessitated a more mathematical, and
hence more sophisticated approach to the subject. Despite this, we have
endeavoured to preserve sufficient readability to enable the busy business
manager to gain relatively painlessly, an understanding of what Operational
Research is about. Whether or not we have succeeded is now up to you to
judge.
Preface ix
I have taken the liberty of writing the first chapter from my own personal
experience as a manager using Operational Research techniques, in the hope
that it will encourage other managers to follow suit. The other chapters have
been written, in the main, by one of us and then revised by the others.
W.E. Duckworth
Fulmer Research Institute Limited,
Stoke Poges
May, 1976
REFERENCES
Duckworth, W.E., A Guide to Operational Research, Methuen, 1962.
First International Conference on Operational Research, E.U.P., 1957.
Waddington, C.H., Operational Research in World War II. Operational Research
against the V-Boat, Elek Science, 1973.
ACKNOWLEDGEMENTS
Much of the material used in the earlier book which was reproduced from
various publications has been reprinted, and permission for its use is grate-
fully acknowledged. New material from Technological Forecasting in Pers-
pective by Jansch, the Open University and The Limits to Growth by Meadows
and colleagues has been incorporated and permission for its inclusion is
also gratefully acknowledged.
Many thanks are also due to many colleagues, especially D.G.S. Davies,
who read the manuscript critically and helpfully and contributed to Chapter
8, and to Mr. R.F. Flint who helped to prepare the index.
Finally, but by no means minimally, we owe much gratitude to Mrs. Joan
Tarrant who typed an incredible number of scripts with patience and
fortitude.
1 What Operational
Research Is
and Does
Operational Research is the art of winning wars without actuallv
fighting.
Arthur Clarke
What Operational Research is
Operational Research (O.R.) has never been an easy subject to define,
comprising as it does the application of several scientific disciplines to the
solving of complex problems in the management of human affairs. The
Operational Research Society of the United Kingdom have the following
official definition: 'Operational Research is the application of the methods
of science to complex problems arising in the direction and management
of large systems of men, machines, materials, and money in industry,
business, government, and defence. The distinctive approach is to develop a
scientific model of the system, incorporating measurements of factors such
as chance and risk, with which to predict and compare the outcomes of
alternative decisions, strategies, or controls. The purpose is to help manage-
ment determine its policy and actions scientifically'. At the time of producing
this definition there were some 38 others which all have merit, and no doubt
there have been many more produced since. I myself prefer to regard Opera-
tional Research as the study of administrative systems pursued in the same
scientific manner in which systems in physics, chemistry, and biology are
studied in the natural sciences.
The problem of definition really arises because language is a classification
process and the more complex a process becomes the less easy it is to define
it in language which can convey a roughly similar meaning to all its readers.
The more precise such a definition is in describing particular attributes of
Operational Research the more it can be resented by the physicist, the
mathematician, the economist, the sociologist, the work-study man, etc. as
encroaching on their particular preserve. It is quite true that O.R. does
encroach on these preserves but if it is any consolation to the gamekeepers
it is a poacher that treats many such preserves with the same indifference
to plunder and ought to continue to do so.
1
2 A guide to operational research
A further problem of definition is that, while it is often easy to describe a
profession or trade in terms of the tools used (there is for instance little
problem in understanding the role of the electron microscopist or the X-ray
crystallographer), any definition which so illuminates Operational Research
tends to give the impression that it isjust a rag-bag of techniques.
It is, of course, more than this but every discipline must have techniques
to implement its means of operation, and to describe Operational Research
without describing techniques would be to attempt to describe a scent without
ever having experienced one. A third major problem of definition is that,
since Operational Research covers a very wide embracing field of human
management, it is sometimes hard to attempt to describe it in these terms
without appearing to usurp the function of management itself.
This is one of the major problems which Operational Research
implementation has had to face since its inception. It seemed at one time that
the exigencies of war had helped to solve this problem, and those responsible
for executing decisions had a close rapport with those responsible for
understanding and analysing the decisions to be implemented. Waddington's
recent book, referenced in the Preface, suggests however that, even under the
pressure of survival against the U-boat, the problems of relationships
between the managers and operational research workers were just as difficult
as they have been ever since.
It is very important for the health of industry that this problem of
relationships should be solved. This is one of the main motivating forces
behind the rewriting of this book. It is a very understandable problem. The
decision maker has to make the decisions. If some other agent analyses, inter-
prets, and resolves them into components and alternatives, what is there
still left for the decision maker to do? There is a great deal. The analysis of
decisions by even the most skilled practitioners who have not the responsibi-
lity for making them and for 'carrying the can' still lacks some indefinable
quality; let us call it judgement.
It is this judgement that finally makes the decision viable or otherwise.
It is this judgement for which people are paid high salaries.
They are not paid for the quantity of work they do. They are not paid
high salaries for the amount of time and effort they put into their decisions.
They are paid, as Elliot Jaques has shown, for the quality of their decisions
and for the length of time which has to elapse before the validity of these
decisions can be demonstrated. It is therefore surely more important that the
decision maker should have the most valuable aids to his decision making
that he can obtain. The manager does not however just want masses and
masses of information. It is a standard joke among the uninitiated in
management practice to jibe at the manager who says 'I must make a decision,
do not confuse me with facts'. Unfortunately, too many managers do mistake
facts for analysis and find that they are faced with a completely undigestible
volume of information.
What operational research is and does 3
This makes it almost impossible for them to make a proper decision
because, although they may consider by using their judgement that a parti-
cular course of action is the right one, they feel that it is inappropriate to
take that course of action until they have checked it against the available
information. Because this is too big a task to undertake in the time, they
remain like hypnotized rabbits until the effective time for a decision has
passed and circumstances take over.
What Operational Research can do is to analyse the available information,
not just from the point of view of the economist, or the physicist, or the
management scientlst, or the production engineer but, with true scientific
objectivity, to sort out which information is relevant, to sort out which
information from past experience has a causal relationship with the situation
being examined, to identify where information does not exist so that at least
its absence can be noted if it cannot be rectified, and then to attempt to
illustrate the likely outcomes of certain courses of action based upon the
information analysed, and only on the information analysed.
The objective of the study is to gain understanding of administrative
systems so that they may be more readily controlled, just as systems in the
natural sciences are more readily controlled than they were and can in fact be
harnessed to man's uses. Incidentally, the word 'control' is used throughout
this book in the regulative and not the restrictive sense.
We can now switch on an electric light with a good degree of probability
that the bulb will light up. We can spray crops against certain diseases with
a strong expectation that protection will be assured without the occurrence
of unforeseen side-effects. But can the average manager be as sure of the
workings of his administrative system?
Can a manager reduce his stocks to a particular level and be sure that he
will not endanger his productive processes or let his customers down? Can
he change his distributive outlets and know that he will be better off? Can he
in fact introduce changes in routine and procedure without considerable
uncertainty as to their results?
Does a manager know very often whether a change is necessary or even
desirable? Modern industry is so complex that the optimum point of opera-
tion of many of its systems is no longer within the intuitive comprehension
of individuals.
To enable this intuition, this imaginative judgement, which is at the core
of management to hold its rightful place in the controlling of such systems
is the function of O. R. Its job is to study these systems and to understand how
they may be controlled by simple rules. Managers often feel that scientific
methods are a threat to their intuition, but I hope to show that the opposite
is true.
If you doubt the ability of simple rules to handle complex situations,
consider how the simple rule 'drive on the left' prevented chaos on the roads
