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It is now ten years since some slight experimental evidence was presented which appeared to support the hypothesis that there was an inverse relationship between recall and precision. The idea of this was certainly not new; Fairthorne had more than implied it in his discussions on OBNA and ABNO systems, i.e. Only‐But‐Not‐All (high precision) and All‐But‐Not‐Only (high recall). However, it was one of the propositions arising from Cranfield I which met with strong opposition and was quite rightly attacked. In reply to the critical review by Swanson, I had to agree that the simple hypothesis required modification. By the following year test results coming from the experiments by Salton and from Cranfield II made further modification necessary, and the hypothesis was finally put forward to read as follows: ‘Within a single system, assuming that a sequence of sub‐searches for a particular question is made in the logical order of expected decreasing precision, and the requirements are those stated in the question, there is an inverse relationship between recall and precision, if the results of a number of different searches are averaged. This, it will be noted, has four important qualifications to the basic statement.

Many of us feel that as a result of the Cranfield experiments we ought perhaps to know something that we didn't know before and that this knowledge ought to have some positive effects on our work—the difficulty is to be sure exactly what these effects should be and what we ought to be doing about it, other than acquiring guilt feelings. During the period of the Cranfield experiments I myself have also been engaged, on a less impressive scale, with similar problems in different fields of knowledge.

Interest in the objective testing and evaluation of document searching systems and procedures has grown steadily during the past decade. The reason for such interest is perhaps obvious: a great deal of attention has been, and is being, given to the development of new methods, including mechanized methods, for storing and searching characterizations of scientific and technical documents. To determine the effectiveness and utility of these new methods, particularly in comparison with the more conventional methods still in use, we need objective means of assessing their performance. Although some progress has been made, much remains to be done on the development of evaluation methods and criteria, a high priority area of study in the view of many individuals and organizations.

The evaluation of information retrieval systems has recently become an important matter. In the past, however, most reports or proposals on this type of work appear largely to have ignored the efficiency of operation of the central core of an IR system, namely those operations concerned in the compilation and use of the index. The only aspects to receive consideration are the physical form of the index and the design of thesauri or classifications. The former activity has been slanted towards the use of computers and has tended to assume that this type of equipment will, ipso facto, give an improved performance but has made no attempt to justify cost factors which may be one hundred times that of conventional techniques. Work on thesauri and classifications, where it has been practical in nature, appears to consist of compiling lists of terms which go out of favour as quickly as any list of subject headings in the past; the more popular theoretical approach is the setting up of models or the use of increasingly abstruse and complex algebras. From the results and conclusions of the experimental work at Cranfield, it would seem that many of these investigations are comparatively trivial.

My task in this second introductory paper is to attempt a review of the research that has been undertaken in relation to the retrieval of information. It is some twenty years ago that the term ‘information retrieval’ was first used, reputedly by Calvin Mooers, although it was several years later before it became a generally accepted term. It would be absurd to suggest that there was no such thing as information retrieval before the term was coined, but it is useful to consider it as marking a new approach to a problem that had always existed, but which had become very much more serious in consequence of the great increase in scientific and technical literature during and after World War II.

The last CRG Bulletin, no. 7, dealt only with the practical application of four faceted special classifications.

A study of the number of irrelevant documents retrieved in a co‐ordinate indexing system that does not employ either roles or links. These tests were based on one hundred actual inquiries received in the library and therefore an evaluation of recall efficiency is not included. Over half the inquiries produced no noise, but the mean average percentage noise figure was approximately 33 per cent based on a total average retrieval figure of eighteen documents per search. Details of the size of the indexed collection, methods of indexing, and an analysis of the reasons for the retrieval of irrelevant documents are discussed, thereby providing information officers who are thinking of installing such a system with some evidence on which to base a decision as to whether or not to utilize these devices.

Computer‐aided systems for all four of the conventional divisions of the field of library housekeeping are now operational in libraries. In Great Britain the only activity not yet operational is that of periodicals control, although two libraries have already used a computer to produce lists of periodicals holdings. The aim of this paper is to describe simply how computer‐aided housekeeping systems work, from the point of view of the librarian, and to mention briefly some typical applications of each type of system.

Publication of the Aslib Year Book is to be discontinued. A full and up‐to‐date list of Aslib members will be published in 1963.

Those of us who look back on a lifetime of work in librarianship, documentation and education—what is nowadays called communication—are often tempted to try to define our terms. Subconsciously we are probably trying to separate the sheep from the goats. Precision in terminology is necessary, especially in the sciences. But what I am going to talk about is more akin to the arts. I would like to take a more general, broader view of our function, our stake in the continuity and the quality of civilization as a whole.