- 1 -CHAPTER 1
Introduction. If two scientists disagree on any issue, and the issue
is within the ambit of science, then it must be possible
for them to agree on a procedure which they can both
accept as a critical test of their points of difference.
For reasons of personality they may not be able to get
together to work out such a test procedure, but it must
exist as a possibility. If such a critical test cannot
be imagined as possible, then the issue between them is
not a scientific issue. The scientific method does
not vary with the subject-matter, but is the sameirrespective of its results and basically the same in all
the sciences.
L . T . Wilkins:

Social Deviance, page 4.

In reviewing the final report on Cranfield I, N.D. Stevens (Ref. 1)
described it as being 'extremely complex1; even after 'several carefulreadings' he found parts of it 'still bewildering', and said that 'there areso many side issues that the author neglects the clear and detailed
presentation of the main headings; the reader finds himself sidetracked
by these, or other interesting diversions'. Since this reviewer was
by no means the only person who made such comments, it has been
our particular endeavour in this report to make quite clear what hasbeen done, how it has been done and what has been the outcome, eventhough at times this has lead to what some people may consider undue
verbosity and repetition.
In one respect, this project is easier to report, for, being in amore concentrated field, it does not raise many of the side-issues such as indexing times, indexer qualifications, etc. - which came up
in Cranfield I and which were sufficiently interesting to sidetrack thereader. On the other hand, to those who have been involved in Cranfield
II, the earlier project seems to have been child's play to what has now
been attempted, and the complexity of the present work is inevitablyreflected in what has to be reported. To those readers who, like ourselves,
tend to view with dismay the many papers on information retrieval which
consist substantially of some twenty pages of mathematics, we can only
apologise that it has become necessary to introduce a number of equations
into this volume. However, it is certain that there is no mathematics

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which should be beyond the comprehension of a schoolboy of average
intelligence, but, even so, it is suggested that Chapter 3 might beskipped by those who are not closely concerned with the particular
problem of performance measurement. Important though the work inthis Chapter is felt to be, yet the arguments may well be of marginal
interest to many readers. At the beginning of Chapter 4, which presents
the main set of test results, full information is given concerning theperformance measures which are actually used; Chapter 3 explains insome detail why those measures were selected in preference to otherpossible measures.
To a lesser extent, the same is true of Chapter 2 which discusses
at length the variables which were being investigated and the environment
in which the test was carried out. Again, we have tried to make
Chapter 4 complete in itself in that such matters are briefly recorded
therein. Only if the reader is puzzled as to why such seemingly
unnecessarily tortuous actions have been taken, need he refer to Chapter
2 to find the possible justification.
The test results presented in Chapter 4 make up the main bulkof the report. Some may cavil at the way in which, at the slightest
provocation, we include plots of the results. Undoubtedly these add tothe bulk, but we can only hope that they will allow readers more quickly
to get a general idea of what has been happening. The following chapter
presents substantially the same set of results in a simpler but probably
more controversial manner. In Chapter 6, extracts have been taken fromthe main test results and presented in such a way as to illustrate different
aspects of the investigation.
Subsidiary to the main test was an attempt to make a comparativeevaluation of citation indexing and bibliographic coupling. While there
should be no serious problems in making such an evaluation underoperational conditions, the value of testing this form of index in an
artificial environment appears dubious. However, with considerable
reservations the results are given in Chapter 7.
Up to this stage the results have been presented without any
attempt being made to draw conclusions. All such have been relegatedto the final chapter of this volume, in which an attempt is also madeto relate the results to other investigations in this field.
There is one general apology that should be made and that is forthe introduction into this report of yet more jargon. Many terms firstused in reporting Cranfield I now appear to have gained general acceptance ,but it is unlikely that such phrases as 'maximum starting term coordinationlevel method1 or 'proportional coordination level method1 will crop upvery frequently in the literature - and we certainly hope they won't - butit has been necessary to find terms to describe certain procedures so that,in reports of other tests, one has a chance of knowing which of several

- 3 -

possible methods has been used. We can only plead that we have not- as some apparently delight to do - concocted new terms to describe
measures or methods when existing terminology has already appearedin the literature. If we have offended in this way, it was unintentional
and we hope that our attention will be drawn to any lapse. The only
case of which we know is where a term has been changed from thatused in Volume I. The term generality ratio T has been dropped infavour of generality number 1 . It is hoped that the argument in Chapter
3 will provide the reasons for this change.